I wouldn't take this and have never taken such a ludicrous risk as buying someone else's position on a game that I wanted to bet on anyway. You do realize that if you've been there when the bets are being tallied you could've saved so much money and still earn arguably even more money in the process without paying so much money as what you did right now. Good on you for not losing it all but 9 times out of 10 this wouldn't be the case, trust me, and you just got so lucky today.
I'd never go so far as to become stupid for gambling to the point that I'm buying someone else's bets in hopes of winning whatever they could. It's like an investor paying/funding a business that doesn't even exist yet in hopes of earning money in the process. It's not gonna happen. Call me condescending or cynical but it's just not for me, and I think a good amount of people in this forum would agree with me as well.
I would not even call it being cynical, this is simply being a realist, whenever someone makes you an offer you always need to think what that other person is winning by doing so, since it is very rare that someone else is going to actually offer you a deal that is beneficial for you and instead they are looking out for themselves at all times, so if I was given this kind of offer I will immediately reject it since my first impression is that I will be disfavored if I did accept it.