"It's fair to say we were in such a bad position financially that if Tottenham had have done their work early, then I’m sure he would have been a Tottenham player," said then-boss Bruce. "Before the takeover came in, everyone was for sale – that’s how difficult the situation was."
Note how he mentions before the takeover.
As for why no one else was in for him, you can ask that question about many players. Why didn't anyone else battle West Ham for Soucek? Pretty sure we signed Son without any competition. Dortmund didn't seem to have to fight off many teams to sign Haaland and he had a release clause too, making it a lot easier to actually begin talks with him. It's actually quite rare for players to have multiple suitors at any given time. Teams often prefer avoiding bidding wars.