[kohanz]

1) It gives me hope that it could turn into something more. You could consider this along the same emotional reward people get from buying a lottery ticket. Whether the odds are worse or better are debatable :)

2) Allows me to learn technologies that interest me but are not used in my day-job.

[mhndrcksn]

1 is great. Everyone knows someone who's certain they're going to cash in big time, and I guess with sites like Flippa it's pretty straightforward to cash in not-so-big sometimes. But like you say, it's more about the ride than the payout right?

2 is interesting - it seems to be that format of learning through use that does it. i.e. The benefits in what you learn from a side project vs. what you learn from a presentation.