There's a big difference between wishing you hadn't let go of something and the wisdom (or lack thereof) that would have accompanied keeping them.
In different ways, I terribly miss my (and there may be a few others I'm forgetting):
1969 Corvette
1970 Cutlass Convertible
1976 Delta 88
1976 280Z
1986 Mustang GT (both of them)
1990 Mustang LX 5.0 (but not so much the '88 and '89 GTs
)
1990 Mitsubish Galant
1991 Miata (despite the fact I still have it)
1991 Q45
2002 325xiT
2004 RX-8
2017 Camaro 2.0T (can I post date this post by a short period of time?)
I've often thought, "I should have kept [any of the above]," but there is not a single time I know that would have been the right choice.
Among us all, FC letting go of the 997TT is the only bad choice for any of us to have moved from any of them.