I'm the son of a man who advises people on retirement planning. I grew up in a home where I was required to save fifty percent of all the money I earned, just to set a good habit. By the time I graduated from high school, I had enough money in mutual funds to pay for my first year at a private liberal arts college (after scholarships, of course). I say all this to note that I probably should have known better...
Crash and burn
In the three years between the time I left for college at 18, and the time I was forced to drop out at age 21, I made a lot of really bad financial decisions. I had joined the ROTC program at my college the spring before I turned 21, not out of a sense of duty, but because I wanted the money. They were going to pay my way, a full ride, and give me a stipend. On top of that, I had qualified for some non-military scholarships and grants that I would continue to receive, regardless of need. In short, I was going to be handsomely paid to go to school and study philosophy. At least, this was how it all played out in my head.
What I did, instead of waiting until all of this came to pass, was spend like there was no tomorrow. I didn't work at all during the summer prior to turning 21. I actually paid for all of my living expenses using a credit card. I used the card I got my freshman year with a ridiculously high limit, and maxed that sucker out. Then, I got another one. Maxed that out, too. No big deal, though. I'd pay it all off when I got my first quarter's payments on my scholarships.