I almost never borrow money, not if I can truly avoid it. I would never ask somebody that I wasn't super close to, so, somebody who wasn't an immediate family member or very close friend (and even then i'd hate to ask, and would make sure to pay it back). I can count the amount of people i've borrowed money from in my life on one hand and still have fingers to spare.
I do sometimes borrow money out here and there to family/friends, especially if I know they really need it, and I have it to spare for a while (smaller amounts I don't mind just giving to them if I can afford not to get it back, and i'm aware that is the case from the get-go). I have no problem with that. However, I don't like to make it a habbit, as some people, unfortunately, can eventually perpetuate an unhealthy cycle of not managing their money and spending properly, and having others enable them to stay doing so- which becomes annoying in time.
Generally the whole 'you borrow from me anytime, i'll borrow from you anytime' relationship dynamic causes me a little bit of anxiety as it's not one that I am comfortable navigating, especially as I am rarely in dire need to borrow (which would be the only time i'd ask).
However, I always try to help, if/when it's needed, one way or another if I am able.