I have been powering up for nearly 2 years now. I never powered down.
This morning I added another 500SP.
I still consider it one of the best investment in the crypto space.
Side note: I do always keep some liquid STEEM and SBD to sell at price spikes, like yesterday. (I sold 500SBD @ $3)
But in general, SP is your motor to generate more steem tokens. It's very valuable.
And it will be more and more rare to earn in the future with more active users per day and a fixed reward pool.
That's why right now there is never a good time to stop blogging.
I talk about it more in my vlog. (start @ 2.45)
I am a witness with our developer group 
for the Steem blockchain. If you want to support us I would appreciate your vote here.
We build Steemify a notification app for your Steemit account for iOS.
Get it Here:
▶️ DTube
▶️ IPFS