Well honestly, it would be kind of out of character for him to keep it. He felt bed bc he didn't win it fair and square cuz Sarah totally messed with the coin and the machine. He has worked his ass off for years to fix a problem he shouldn't have had to deal with because it wasn't his debt in the first place. But he did it anyway and he was determined to live a simple life without debt but he LIVES to WORK, not the other way around. Sohan raised himself as someone who works hard to get things, accepting money when he didn't have to work his ass off, he wouldn't want that because he's grown up to be someone humble and non-materalistic despite his sad upbringing.
having extra money isn't materialistic, it's ensuring you have some level of financial stability or the means to help others. as someone who had to work his way thru everything he knows how hard it is to earn money and to keep a roof over his head. living paycheck to paycheck and not having money esp for emergencies is stressful. i honestly find it ooc that he'd just say fuck it we'll figure it out.
I get that, but consider how he prob also did it to see if his father would stay. To him, it's not a matter of saying "fuck it, we'll figure it out" but a matter of trying to desperately convince himself that his father had grown into someone decent, so it just served as a last resort to see the truth. Anyway, still, not keeping the money because it was planted by sarah is still in character, he probably would've done it sooner if it wasnt for his dad, but probably not by destroying it. I'd assume he'd donate it instead if under different circumstances involving his father. I also think the situation he faced caused him to destroy it, under the possibility that his father would terrorize the people he would give the money to, since the old guy was so convinced that it was his and sohan's money, not sohan's money alone.
i think sohan was really ok with accepting his father with all his flaws and wanted to make do with their relationship with each other, so the money wasn't a last resort to see him as some decent dude. but it probably was him hoping that they could move forward even without the money and he's letting his dad be the one to ultimately make that decision.
it's fiction so it matters less but irl it's super unlikely that someone with financial hardship would be ok with burning all of that away. i wouldn't mind watching his dad try to demand a unicef-like organization to give back the donation tho lol.
did sohan really have to burn his winnings tho like i would readily accept that as karma for having such a difficult life growing up