Well.. yes? A relative of mine is a student and is into electronics. His monthly income (with various bonuses for good academic performance) is around $100 per month IIRC. $5 is a significant sum for someone like that.
Especially when developing something. I let out magic smoke from many a chip over the years (or partially destroyed one of the internal components, rendering the whole chip pretty much useless).
Right. Also $0.1 part you can easily get a few so you have spares at hand or for follow-on projects, with limited loss if it doesn't turn out great. Whereas dumping $50 on 10 of an expensive part is much more of a risk. Especially bad in places where getting parts means expensive international shipping each time: You want to order enough at a time to not pay shipping multiple times (and/or have long waits), but the parts need to be cheap for that to be viable.