Isn't the antonym of hapless opportunistic (without its negative connotation)?
Hapless means being in a situation with no logical way out, such as being stuck in quicksand, or being good at Ruby on Rails.
Sure. I learned Ruby on Rails about 3 years ago at a startup. I've since been trying to do other things for employment, but nobody wants to pay me to do anything besides Rails. Lucky for me, the economy has collapsed so nobody wants to pay me to do Rails, either.
The opposite of... is not...
worthless worthful
senseless senseful
wasteful wasteless
handful handless
moreover lessover (moreunder?)