How to completely unlock a hat objective

I was frustrated with the same issue. I believe that the lifetime coins challenges do not start counting until after the objective is activated (which could be a bug). You probably activated Gold Miner first, collected nearly 400k coins, and then completed a separate challenge that then activated Midas Touch. From that point all coins collected applied to both Midas Touch and Gold Miner, but because Gold Miner was open first, it has more progress. And, of course, the Midas Touch progress bar is going to fill half as fast as Gold Miner's.

I actually stopped playing after I noticed this. Even though they decreased the +2 Gem Powerup to level 9, it will just take too long to complete the lifetime challenges. If it had been counting my true lifetime progress, they would have been completed already.

Edit: with the series of updates up to and including January 2015, there are now enough objectives to make it to level 11. There were a couple of objectives added in a December 2014 update:

• run 5 million meters, less onerous than the 10 million one

• unlock a hat

• run 2000 meters without coins

  and with the two in the latest update (1.12.2)

• run 50,000 meters as Scarlet Fox

• run 50,000 meters as Maria Selva

there were enough for me to complete level 11, which had some gem reward bonus.

Earlier answer, now no longer correct:

I don't believe there are enough tasks available to complete level 10. Previously, there weren't enough tasks to complete levels 8 and 9, but eventually with various updates, new tasks were added and thus those levels eventually became complete able. I expect it will be similar with level 10, so waiting for updates is the only solution I expect.