I drop names that doesn't perform. I feel good that someone captured the domain, and applied their marketing approach. If I see them parking the domains, then I've done that for many years, and it will end the same conclusion.
Yes, I bought names for cheap and resell it for a good return of investment, but not all domains receive the same results.
I prefer to invest my $10, that I know I have purpose, and not rely on luck of selling to end-user.