You have a point here, though the trouble is, they might not be there for you when you need them regardless of the compromises and sacrifices you make for them. People seem to have a skewed way of counting, forgetting that you were there when they don't want to do the same for you.

if you say no all the time people will stop asking

True. There are always consequences to your actions and that s one you should be okay with before you say no, I think. You might be kicking away future opportunities you might otherwise enjoy or you might be relieving yourself of future hassle. One should always think these things through as best he can.
Thank you for commenting :)