First of all, fair play and hats off to you for taking on the whole mob here
On topic, ok, but then we'd have to look at the specific players.
How many of Spurs players are hyped Europe-wide? Pretty much none, because their performances in Europe have been consistently poor.
Now obviously Kane, Alli, Eriksen and a few others are excellent young players who have been performing great in the league, but the hype is just starting to catch on. If they confirm their performances, you will see bigger clubs than Spurs come targeting them for real, and then we'll see how long-term they will be at Spurs.
Another thing is, if Spurs don't make the step up to proper title contenders and a European team to be taken seriously, and they flat out refuse to let players leave under any circumstance that are courted and want out, top talents might opt against joining them in the future if they feel they are joining a prison.
On the other hand,
a) BVB were overachievers under Klopp, with their European exposure not matching their financial strength, so there was a different dynamic at play considering the forces pulling players out. Once Kane scores four goals in a CL semi against Real as Lewandowski did, you'd see what happens and whether he'll still be happy to stay and renew his contract at Tottenham.
b) In Bundesliga, in recent years Bayern, due to our current success on top of our fundamental financial advantage, have much more visibly been a potential step up for players even of BVB. I'd argue that we have more pull over any Bundesliga player than say Chelsea or Man United have over Spurs players, simply because there the difference isn't that big at the moment.
c) let' not forget specific circumstances, like pain in the ass Raiola tormenting BVB to the point where they'd let Mkhi go - it's not a step up from a football standpoint, only from a financial one. Raiola also had Pogba sold to Utd for financial reasons (because Juve are already the far superior team).