I bet if you asked the previous owners they would say that they never had a problem with it! But it sounds like the services were done by garages that were not really up to speed on Alfa's ? . . .so the services were,maybe,just minimal services,just for a stamp in the book . . . .sadly,you got the rough end of the stick!
Some of the most neglected cars I have had,have had 'full service history'!! Including one that snapped a timing belt,10k and nine months before it was due,even though the "service stamp" was present for the service that should have included the belt change . . . . . .
And some of the most reliable have had no history at all . . . . .
As has been said already,you have caught up with most of the issues,now(top wishbones are pretty much a service item,anyway!!)( and with the long bolt put in so the nut is by the strut,very easy to change),so is it a case of 'better the devil you know' ?
It seems a shame that you have paid out to fix all the faults,not to enjoy the best bit of Alfa ownership . . Driving it!
I guess the other side of the coin is whoever buys it next won't so have much to fix . . . . Maybe . . . .