Thousand Foot Krutch - Welcome to the Masquerade Lyrics Meaning

All the people try to hide their feelings and thoughts behind different expressions (sea of masks). Everyone is welcome to join (everyone is free to hide or show their emotions).
The strong people are forced to hide behind masks because they fear losing their strength (monetary power, status in society, other kinds of strengths) but the weak have nothing to lose, so they can be mask-less and fearless.

It can also be interpret as teenage years....boys putting a fake mask to impress girls and vice-versa, while I stay mask-less and am not ashamed of being myself or afraid of losing anything.