USB miners is like the dumbest decision you'll ever make... They profit you literally nothing, especially with the difficulty rising quickly.
Dunno, they make amazing lottery miners. They have a different purpose than let say a S5. They fill a different niche and just like any other hardware, some sticks are great (sidehack stick 8-23GH/s+) some sticks are horrible choices (nano, 400MH/s, etc whatever).
Some people just don't get it. It's for the fun on this section of miners either fun or learning. Chances of making money is slim off of them I think everyone know's that. But you do it for the fun.
And yes I have much bigger miners that are for profit. So I don't do all with no goal of profit. But a few out there are fun especially with things like the compac group working together, we can run our compacs for very cheap for a long.. long time. My U3's on other hand a little more costly but still fun.