Confido already picked it up and is using it and says their company would be near impossible to run without chainlink.
But yeah you are right. That is the entire gamble and risk, If it was a sure shot everyone would buy it.
The same was said about ETH at the start. "what if no one uses smart contracts or just program their own solutions as a smart contract seperate from the ETH chain"
Bottom line is you buy LINK cheaply now in the speculation that it will get adopted in the future.