Well, you know, if you are fighting outnumbered, you sadly cant build glasscannon and expect to live through enemy damage unless you are a nightblade with clock, but even they have to build somewhat tanky, since damage is way out of control these days.
And if you get killed while trying to outnumber a single player, then you are literal 1vX material and you should seek out for help and try to get better rather than spam "lfg" every 2 minutes in zone chat and then complain on the forums about not being able to win every fight just because you outnumber the opponent.