How much can you milk from a weak player?

[Jman28]

I mostly play Party $20 SnGs, and I've realized, many times when I hit TPTK, and get a flop caller, unless he's on an obvious draw, he will call me down to the river with Top pair 5 kicker.

I assume some people fold hands like these that I don't have to show down, but I think I'm underbetting.

Some of it is being afraid of a set, but I realize that I'll usually call a large raise from them on the end because at least half the time, I'll still be shown that dominated top pair or worse.

Another reason is that I play super tight when 7-10 players are in. But I feel like I could win more in the long run if I could get my winners paid off higher, even if I bust out a few of the times

If a player will call 200 of his 600 chips on the river, will he call 300? 400? All in?

Any advice?

Thanks