1. are you always this obtuse or you're doing specifically for this occasion? your boyhood club and manchester united are not part of the same division/tier in football
2. playing in an european final does not translate to having a better career
3. united is popular. whoohoop.
1. Neither is Crystal Palace and Manchester United
One is a middling Premier League team that occasionally sees relegation or relegation struggle. The other is one of the biggest sports teams in the world with a stadium with a max capacity of 76 000 and sells out every matchweek (pre-corona). Crystal Palace has a capacity of 26000 and is a significantly lesser club with a lesser heritage.
2. Achievements tend to define careers. In fact, achievements is one of the definitions of having a career in the first place.
3. Manchester United is one of the top10 biggest football clubs in the world (no rank assosciated). Crystal Palace (to use one example) slots in around 150. Most professional footballers very much care about reaching the higher echelons of their sport. Scoring at the Stretford End in front of 76 thousand roaring football fans tends to put a bigger impact on a player than a home game at Selhurst park. The two aren't comparable clubs. The only thing they have in comparison is that they play in the same football league.
You're arguing that nothing matters unless you win, which is frankly a little bit depressing. Learn to enjoy the journey.