Late adopters will be benefited like any other Bitcoin adopter, although the potential profit they may make by investing in BTC is much inferior than the profit made by early investors who adopted Bitcoin when it was still pricing less than 100$ each coin. So far the other means to get extra profit by adopting Bitcoin involve risks, like lending it at third party platforms, so it's not advisable in every cases and in many situations it has been unprofitable, since investors have lost money to scammers.

The best you can do is to continue holding until and expecting the price to rise on long run. Just don't compare the current profit you are making to the profit people used to make in the early days of Bitcoin adoption, otherwise you will indeed feel frustrated because the investment isn't being so profitable like you wished it to be.

However, don't forget that even though profit has been decreasing cycle after cycle, it's still a much superior investment when compared to traditional alternatives offered by fiat banks.