5-10% of day traders will trade profitably over the long term,...

5-10% of day traders will trade profitably over the long term, and their fodder is the contributions of the other 90-95%. Very hard to win over the course of say 5 years, but if you can, you'll be quite wealthy. Brokerage cuts into it a fair bit, but there's also those psychological factors that a lot of us lack.

I'm starting to think that longer time frames contain significant risk too, given what we're seeing with blue chips.

There's an optimum time frame somewhere in between, I reckon.