Conventional wisdom advises not to try anything too hard because you might fail. True, but that advice discounts the biggest dividend of all: who you become in the process.
I didn't realize how important this was until I saw how easy it was for me to do most ordinary programming gigs. It was like playing basketball with a regulation hoop when I had already practiced with a smaller one. Other programmers struggled because they hadn't seen that problem before and they had never stretched themselves.
Building hard things on my own made me a much better programmer when I did work for others. By far, my best investment ever.