As long as you do not have checked bags.
AND most importantly, it is not part of a RT ticket.

Basically - if you "miss" your connection, you are all set.

I assume this is because the longer ticket is more expensive and you are saving money by doing this. Called hidden city ticketing. Though not "allowed" by the airlines, it is hard for them to manage.

P.S. There is a situation that could cause you an issue. You bought a ticket from ABQ-DEN that happens to stop in in OAK. If there are flight disruptions, the airline could put you on a nother flight to Denver that does NOT connect in OAK - screwed.