Your family is not right, but in fairness to them you can probably give them the benefit of the doubt and assume that them warning you about this motivated by a desire to protect you. There are plenty of girls your age who find older man attractive, and many of those wouldn't even consider guys in their 20s to be 'older' for these purposes, but it's also right to say that there are plenty of older guys who are very willing to exploit and take advantage of girls your age. So the concern for your parents may well be that in pursuing older guys you'll put yourself in situations where you're vulnerable or otherwise not entirely safe.
Of course, as a headstrong 17 year old you're going to dismiss some concerns as coming from over protective parents, but it's not just the risk of you being physically harmed. There are plenty of situations where you can be intimate with or have sex with guys of any age and regret that decision later, because it's not something you thought through or because you feel with hindsight that you weren't entirely comfortable with it. That's not necessarily a bad thing because to a degree you have to learn from mistakes like that, but it is right to say that you should make sure that you are sensible and stay safe in situations like that. It is entirely up to you who you find attractive, who you get into relationships with, and who you are intimate with. But it is also fair to highlight that you should make sure you're keeping yourself safe whilst doing so.
It's fair to say that much of this applies regardless of the age of the guys that we're talking about, but I do think the risk is somewhat higher, for several reasons, when talking about older guys. It's just something to be aware of, and I don't think you should judge or criticise your family for wanting to protect you in that situation (not that you have in that first post).