can i not use dental floss to sew?

hi everyone, i started my first pair of patch pants recently with materials i have around the house, because i cant afford to buy anything new. I dont own black or white thread (only a light pink one which i dont want to use) so i used dental floss, i was happy how my pants were starting to look so i excitedly show my punk friend, he took one look at my pants and said “wow you used dental floss because you don’t research subcultures”, i asked what he meant and said “i only used things i had already” and he just sighed and changed the subject, what did he mean? i genuinely cant afford to spend an extra dollar for thread and im kind of in a depressive state & these pants are giving me something fun to do, please educate me thank you..