These are some of the few ways you could earn cryptocurrency. Most of these are investor related and does not require a special set of skills (other than market analysis and basic cryptocurrency literacy ).
Trading
Yes, I'm sure your social media is filled with these "gurus" who sell trading courses on cryptocurrency, but beyond them scamming you, this is perhaps the most common demographic in crypto space. Majority of initial investors have backed out due to non-belief, or they have lost too much due to FOMO in December 2017. Some of these traders invest in any currency they can receive a sizable profit percentage wise. Although markets are back around the prices they were before August 2017, the massive gold rush mentality around crypto has paved the way for ICO's to grow and proceed to make their ideas come alive! My favorite is peer-to-peer trading oppose to trading centrally like Binance or Coinbase. This method of trading maintains the decentralized philosophy of cryptocurrency. These sites include those like Paxful My personal favorite and r/Cash4Cash.
Mining
Mining has been the driving force in cryptocurrency value generation. In the early days, mining took little computational power for the gain of so many coins. Granted they were not worth $4000 as they are today. With 17 million BTC mined and the block reward halving every 4 years, for a time, mining was a profitable avenue for generating funds in crypto space. It got to the point, mining operations began to become centralized with mining pools and scammers setting up bots to give user's the illusion they are earning a lot when in reality, not much value is being produced. As more users join the network, mining is not as profitable as it used to be, and miners have to sell off most of their currency to pay for energy cost. If you don't have a solar panel on your roof or a wind turbine in your backyard, then it's not worth getting into.
Hodling
This is the goal of holding on to your crypto's for long-term gain over time. It's less of earning crypto and more of locking away assets. Cryptocurrency is considered less of "currency" and more money. Currency in the sense it's the representation of a value used in medium exchange, while money is the store of value for medium exchange. The hodl method is viewing cryptocurrency as an asset like gold, art, or real estate. This distinction in attitude brought the rise of coins vs. tokens.
I personally think this is a problem in the cryptocurrency community. The "Hodling" of coins for long-term gain when your BTC will be worth enough to buy a Lamborghini is a strategy, but without an actual incentive for use of the currency than it simply just dies. This is a reason why XRP rose to the number two spot. It gave an incentive for the bank to use to cut transaction cost, and it proved that it could act independently from its crypto counterparts.
ICO Investing
Ahh, don't you wish you go back in time and by Amazon stock in 1997, Apple stock in 2000, or Bitcoin in 2009-2013? Well, ICO (Initial Coin Offering) is similar to stock market's IPO (Initial Public Offering) for companies. Tokenizing is usually referred to owning a decentralized currency that you can use a form of payment, or store of an asset for a project built by an entity. From 2016 - Today, there have been numerous currencies launching ICO, with around 2000 listed on exchanges and excluding those private ones built by individuals for test purposes. With an introduction to Ethereum and Vitalik (Badass name by the way), it made it seamless for developers wanting to build ICO's and launch projects surrounding a goal. Many have failed while there are so many out of the ICO stage and into the development stage.
Investing in an ICO is extremely risky on the account it's not regulated and the chances of you receiving your funds are low. However, they can be extremely profitable when it launches to the public. The FED, Banks, and SEC has placed heavy restrictions on ICO's due to scam practices by illegitimate companies. This is why Google, Facebook, and other online sites outright reject any crypto project or idea that is not formally introduced to the government or business market.
Master Node
Masternodes support the cryptocurrency philosophy in the way they are decentralized and anyone can operate one. However, unlike mining where you just need a computer, some blockchains place a barrier onto the requirements of a master node to ensure there's little room for errors, corruption, and discrepancies. This is what's called an entry barrier. Entry Barriers is what one needs to own or collect a certain amount of units of that particular cryptocurrency to input into running a masternode. Unlike Bitcoin's blockchain that works off proof-of-work, in laymen terms "mining", Masternode is proof-of-stake, which Ethereum blockchain operates off of.
This motivates the masternode owner not to cheat or corrupt the system. In the event something faulty occurs on the by Masternode accord, they are ejected from the system and their Entry Barrier will be out of their possession and ownership.
This can be profitable for long-term investments because the factor is less on earning cash then, and generate "passive income overtime". Some cryptocurrency algorithms payout daily, weekly, or monthly interest for running a masternode. The fiat equivalent of this would be a high yield savings account. Instead of the centralized system taking your "money" and loaning it by fractional reserve banking, you are the master node for holding the stake to run a piece of the blockchain system. Through holding a sizable amount of stake, you will be given the status of the Validator to verify blockchain transactions.
Other Ways to Earn Crypto
Offering a good/service and receive crypto as payment
Participating in dApp Communities (Post coming soon)
Coding your own blockchain/smart contract
Coding your own cryptocurrency