I don't know how you define 'neutral football fans', but my impression of what you are saying is that only locals and people who inherited supportership from a parent or sibling started supporting Spurs during the two decades you mentioned.
It's not true, obviously. I'm amongst the foreign fans that started supporting the club in the early 90's. Mostly because of Thorstvedt, because he, like me, is Norwegian.
So kinda like the koreans with Son.
Expect some of them to stay Spurs forever.
I want them to stay forever not come and go once their favourite player leaves. I get that fans no longer support their local club as the premier league is commercialised and now a global brand. We've had a long history of players from Scandinavia and appreciate fans coming from there because of those players. Same with the likes of Sonny now. I found the comments about the calling of some fans 'dumb shits' and town idiots a bit disrespectful to supporters who have lived in the tribal atmosphere of North London. Players come and go, the club is my overriding passion.