I think saying he isn't a friend is wrong.

I've had good friends who are shit with money and helped them out - as long as they are paying you back when they say I wouldn't call it taking advantage.

If they think you don't mind and are cool with it (and OP says he has loads of money) they probably think it's just no big deal and for a lot of people it isn't (as long as it's paid back).

Having been in a position with no money and also in a position to lend at times I'd say sometimes it can make a huuuuuge difference to have someone who can ride you over for a few days and if you've got the money and its meaningless to you why not do it.

There are people who can take the piss but generally I don't see anything wrong with a friend asking to borrow cash if you've clearly got loads.

They likely would do the same without hesitation if and when it's ever the other way round. At least that's how it's always been for me.

If you've never been really hard up you might not know how life or death it can feel to get 20 quid for a week or so.