There is a bit of difference between friends, and "friends" if you know what I mean, i'd lend a proper friend most things. (and have) sometimes I haven't gotten these things back, other times I'm just yet to get them back.
For example I have a friend who borrowed a de-humidifier about five years ago, I don't need it, - that's why I said he could borrow it when he was talking about buying one. and a part of not needing it is I wouldn't be that fussed if i never got it back.
I've got about a quarter of a grand in recording gear (perhaps more actually) lent to a mate on a long term loan, (though that guy is more like family than a friend.)
On the other hand, I've got "friends" who I wouldn't lend anything to.
I tend to find it is family who lets you down the most with lending stuff though, I guess their thoughts might be that you can't stay mad forever, or maybe it's me thinking their family, they wouldn't let me down!
but i've lost no end of computer related stuff just lending it to people. (family)
Back in the Win XP days, I had an MSDN subscription so had all the various Windows versions. My son would ask to "borrow"an XP install disk. I'd never see it again. This kept happening so I eventually told my son, "No!", when he asked to borrow an XP install disk. I told him to use the others that I had lent him. Turns out he was giving them to his friends.
in my big bag of CD's, I've got some borrowed MSDN CD's (well copies of) they are all marked, From 'xyz MSDN collection, rather than just windows XP specifically so I don't give them away, I never wanted a friend to get found using pirated software, for that to come back to me, and then onto the good friend that had lent me them in the first place!