Let's say you pony up rent for your YCombinator startup and are paying about $2400 / month + utilities for 3 months. Let's say you get your food & other necessities costs to $80 / week.
That's an $8160 investment.
What you get back are the weekly dinners with great speakers. The connections you make should be worth at least $150k if your startup fails and you have to use that connection to get a job. I'm assuming a markup in your value as an employee for just getting into YCombinator.
$8160 and you can make 20% - 35% more than your peers if it fails.
$8160 in lottery tickets will pretty much get you zero if you fail.