This season is pretty weird for Manchester United. Total failure in the Premier League and going to a Europa League final at the same time.
I can assume that the players are way more motivated to fight for a European trophy and totally not motivated to put any effort in the remaining games of the English Premier League. Tottenham was also a failure in the Premier League, but a success in the Europa League. Two things come to my mind. 1.The Premier League is very competitive. 2.The English teams playing in tournaments like Europa League and Conference League are way too stronger for their European rivals. Anyway, I would put my bet on Tottenham winning EL, mostly because they are viewed as outsiders.
Choosing to watch Manchester United instead of Tottenham matches because Manchester United is the first support team since I knew them. Yes, even though being a Manchester United fan has been a joke from friends.
I am also a Manchester United fan, and I clearly understand what you mean by "being a Manchester United fan has been a joke from friends" because I know what I face at the hands of my friends and brothers who are supporting Liverpool, Manchester City, Chelsea, and Arsenal, respectively. Even though I am not a Manchester United fan, I would still choose to watch the Manchester United match with Athletic Bilbao over the Bodø/Glimt match with Tottenham Hotspur because the Manchester United match with Athletic Bilbao is more interesting to watch than the Bodø/Glimt and Tottenham Hotspur match.