Failure 1: I'd planned to do a PhD eventually, but I ended up more or less self-sabotaging my degree grade by being depressed and not doing anything about it (2:2 in the UK system vs. the nominal 2:1 ostensibly required for MSc/PhD applications to most places)

Failure 2: For the longest time, I never managed to make a good routine for myself. To learn, build things, exercise, meditate, etc. Good habits seem to be a pre-requisite for success in virtually any endeavor.

Failure 3: I had an interview scheduled with Google once, right after I had finished my military service in Finland (it's more or less mandatory for men).

I had scheduled it a tiny bit too close for comfort, just after I was supposed to have been out of the garrison. Turns out they called an hour too early (I specified UTC timezone but they marked it down as BST..) so I could only awkwardly tell them I could not talk at the time, and ask if they could call again an hour or a day later.

I never could get another call and settled for a crap job (by some standards). Maybe I could have earned a lot more and learned a lot more (and had a better network of contacts) if things had turned out differently :p

On a more positive note, I started doing freelancing/consulting last year after "no one" seemed to want to hire me at a decent salary and proceed to make OK amounts of money through random gigs.

Still figuring out how to network effectively. I figure the best bet is through gaining visibility online by publishing something useful.