long term it tends towards zero and most of it was frittered away on players IIRC.It's significant because whatever proportion of that was spent on capital (and I have no idea what proportion that is) still remains and has the value of the club at a higher level than it would be had said capital never been purchased. To put it simply, if he invested at all in facilities, presumably those facilities are still there and are worth more than the previous ones.
for villa and lerner it is now long term. they are comparitively no better off than when he started pouring money down the sink.
The rise in the value of the club will be due to nothing but inflation.