1/125th of a second to snap a photo, sell it for thousands, BOOM!
1/125 second is a very normal shutter speed for a photo, but I often use speeds less than 1/400 sec, and you can go all the way down to 1/8000 sec on a sunny day. Think how fast that is!
One click, a fraction of a second, and then you can sell that photo for pennies, cents, euros, thousands of dollars, all the way to millions even if you get real lucky. You can sell the rights to use a photo, from a stock site, thousands and thousands of times over and make a little more every time, passively. You can also sell prints, making money off of the same photo, thousand times over again.
Think of professions where you can make a lot of money, like a stupid amount of money; NHL players, NBA players, Formula 1 drivers money. They make thousands in minutes, but as a photographer, you have the potential to make even more in a fraction of a second. I made about 12€ per hour (minus tax) as a chef, so you can only imagine how excited I am about the prospect of doing photography for a living.
This is of course written very much tongue-in-cheek fashion but it’s to highlight a point that photography is a business of catching that fraction of a second moment. In reality most photographers are starving artist.
All the thousands of hours of work you put into learning photography, finding subjects, doing assignments, the endless hours of tweaking pictures on computer, creating your own look, comes down to that fraction of a second that can make your whole career.
All the preparation and practise is put in place for that ability to capture the moment perfectly when/if it represents itself. And the IT moment might never come.
Of course you can increase the possibility of getting that amazing shot by putting yourself into a place where there is a greater chance for you to see something spectacular happen, or you create that moment yourself. I think often a photograph might only gain its value after years and years of it being taken. For example people die and the pictures taken of them instantly become more valuable, at least to the people who were close to them. Some become politicians or rock stars, and the pictures of them taken prior to that gain more interest from the public.
Keep shooting, keep practicing and back up your work!
Picture credit goes to 
PS. tried to upload this through Steempeak like I usually do but it refuses to do so because of an error saying this contains letters outside Latin1. Usually that means there is either Ä or Ö in the picture name but this time there isn't.