I'm not Mike, I want nothing to do with that AL shitstorm.
Seriously £10 is not a big deal, it really isn't.
Those admin fees are for all the messing around people have to do. So first of all, I know that card payments through Stripe charge £1.75 as a base rate, then 10p for every £1 when the amount exceeds £1.75 (£18+), same in the reverse, so refunding someone AT A MINIMUM through stripe costs £3.50, then you have to bear in mind that the event has to purchase stuff before it runs and pay for the venue and crap. So you say "Well surely they aren't using that money", they probably are.
Stripe is the cheapest option too, paypal takes a bigger cut.
For the record I know the cut stripe takes because i'm a web developer. As for what they spend their money on, I don't know for sure, but I'm not an idiot, I can work out from renting things that you have to pay up front.
Also Mike has to fund his "endeavours", completely legit obviously, nothing illegal...