I don't disagree with anything you've said. Its all true. But remember its just a chance. Even if we do get lucky, real success doesn't always come with a top5 pick especially with this years so so draft.
Lets look at last years draft (actually a pretty good draft).
#1 pick Cade Cunningham Did he make Detroit significantly better ? He's a good individual player but Detroit is still bad.
#2 pick Jalen Green Same as above. Houston stinks as well.
#3 pick Evan Mobley He has made a big difference for Cleveland. He's what I think you and most spurs fans are thinking when talking about tanking. Got to tank and pick wisely.
#4 pick Scottie Barnes Definitely a good player and has made Toronto better but still a middle of the pack team and first round fodder. Hey we should have their next #1 pick !
#5 pick Jalen Suggs Even with 2 top 10 picks they are still at the bottom of the standings. At the bottom, they won't need that much luck for a decent pick.
We both know that the spurs will need a lucky bounce to get a decent player and even then it doesn't always pay off immediately. The teams above were pretty bad or just lucky enough to move up a bit. I believe in luck like everyone else. A good pick helps, I just believe more in trying to play better now rather than tanking and waiting a year or two or three down the line for it to pay off.
Like you said we're a small market team and with our past history, culture and reputation, the spurs tanking, especially if its obvious like some other teams, is just not a good look no matter what the benefits.