5000 coins @ $15 cost the $75000 to buy. Think about it this way, even if you had known about bitcoin back then, would you have been willing to gamble what probably amounts to the average persons life savings into some barely heard of internet fad. Sure, it's easy to look back and see bitcoin as the sure bet, but when it was $15 it was small and nobody knew where it would go.
Yeah, but in 2010, bitcoin was a barely heard of crypto paper with no exchanges. To get in you would either have to mine it yourself (probably using command line tools with a bunch of manual steps) or find someone to buy from in person or on a mailing list. That's a lot of effort for something that at the time just looked like a cool 3rd year project.
For every person that picked bitcoin and made a gamble, there are 1000 people regretting that they invested in some other idea that just quietly didn't go anywhere. Investing that early is not much different to gambling. You probably have better odds of winning the lottery that picking the next bitcoin.
