Misfit

[ROBINDESBOIS]

How can I use the plural of misfit.
Eg.
Many people sleep in the rough because they a social misfits.

[JPablo]

How can I use the plural of misfit.
Eg.
Many people sleep in the rough because they are social misfits.

I think your usage is fine.

Another example,
A new study has suggested that people who are deemed social misfits or 'losers' are ineffective leaders...,