Is accepting voluntary sacrifices from others moral?

Imagine that someone offers you a way to increase your wealth, lengthen your lifespan, or achieve your goals at great personal cost to and even sacrifice of himself. Is it wrong to accept that? What if you've tried setting them straight and telling them to act in their self-interest, but they still insist on trying to be altruistic? Would accepting such a sacrifice be a breach of integrity for an egoist, or would rational egoism urge you to enjoy the proffered benefits, so long as voluntarily bestowed? In other words, is accepting voluntary sacrifices from others different from forcing others to sacrifice to you?