We will be happy to work or sell goods for 1 btc even if we know the price will move in the future.
The increase of true believers, of their revenue and of their networth drives the price up because as they get older, they get richer and as they get richer, they get more bitcoins. The process takes year and increases bitcoin's strengh and bottoms.
It's not a year or 2 bear market that will chase previous true believers and new true believers arrive in the community everyday and it's pushing the price higher.
Along as it exists, the bitcoin will be forever useless and the true believers will use it. More that the profit it gives us, it will be much happier if we use it as a global currency that are free to use anywhere. As long as bitcoin is there, cryptocurrency will makes sense.