No, actually they're right. Stadium upgrades are only to unlock the important facilities like better grass, medical, training and youth. You won't make profit from ticket sales for a long time, my recent 80M+ seats upgrades adds 6500 seats, and will take over 400 home games at my current $30 to give me a profit.

If I have money to spare, though, I will continue to expand my stadium, just because it looks better.