Gaming's first golden age was the Atari, which extended into the Nintendo era.
Gaming's second golden age was the PC, and ever increasing complexity and realism. Though amazing, this type of gaming became an increasingly niche market.
Gaming third golden age is the mobile platform. This reversed the trend of the MMORPG, where more realistic and complicated games defined gaming, and returned us to the simple but engaging games of the Atari and Nintendo eras. Not surprisingly, this brought gaming back to the masses, and that has been profitable. The games are engaging as well for the same reason that Atari games were engaging. They are easy to learn the basics of, but mastering takes time.