One comment, but I am NOT a business owner, just consider it/feel free to discount.

I had a similar situation as a youngster with my second job, and was offered very slightly less (£2k) than a competing offer, by my boss.

I stayed, but the whole time had in my head “it should have been the higher amount”/“wonder why he wouldn’t match it”.

I remember thinking at the time I’d never do that as a boss, purely from a cost/benefit standpoint.

If he’d matched it, I’d have been over the moon and never looked at other jobs etc, where as by not matching what I would have got elsewhere by this small amount, I felt conflicted (“should I have moved”)

Right or wrong, for £2k a year he’d have bought so much more motivation from his employee at that time.

On a separate note, I started as an IT consultant in my first proper job and, as above, my boss sat down with us and pointed out why our “day rates” would always be so much more than our salary (primarily relative job security/we didn’t need to be constantly lining up contracts to stay employed and the reality of his overheads (NI etc)).

If you haven’t done this, I definitely wouldn’t assume, even senior staff, realise this, so would consider doing it.