Someone help me with a rebuy tournament explanation

Okay. I've been trying to play the rebuy tournaments on UB, the ones that have usually had an overlay like the $5k $1 entry one. I think I need some assistance though figuring out the math of it all.

If you enter a rebuy tournament, how much should you reasonably spend? It's a $1 entry fee, or the $2 or $5 on UB, how many rebuys is sufficient?

I see people rebuying 10-15 times, it makes me wonder, how do they expect to get their money back out of it? If you're doing all this rebuying the chips you had are going to someone, so every time you rebuy you're getting in at more and more of an overall disadvantage.

I'm in one now on UB, the $1 one. It's paying out 110 places but in order to get, let's say, $10 you have to end up in the top 80. It just doesn't seem +EV to buyin all those times.

Let me know what you think or what the "book" on this is, if there is a book on rebuys.

I'm not a big fan of rebuys, but i will play them from time to time. I actually just won a 3+.30 rebuy satty to the 50-50 on FT. I immediately re-bought to start w/ 2K and then used my add-on during break. I always like to have an idea of how much $ i'm willing to pay prior to entering the tournament and the prize must be much more than this amount. This is why i mostly play rebuy satellites, you know exactly what's on the line. This being said I don't think i've ever rebought more than 5 times in a single tournament.

most players that re-buy that many times are useless and should not be taken as an example. They will not be thinking about the maths involved.

Try the re-buy tournaments where you start with a decent chip stack and the blinds go up slowly. This gives you plenty of time to get your money in against one of these stupidly aggressive players.