I think it was a myth that the tech was ever the hardest part. Perhaps, it was when you could roll in huge amounts of cash just by offering a digital version of something. It was so easy to market something that the tech looked impossible.

Existing tech is not hard. Tech that hasn't yet been invented is hard. That's where the money is made.

Big innovations are certainly occasionally profitable. But looking at most of the tech success stories of the past couple of decades, there seems to be a lot more money in incremental improvements and applying existing technology to new business domains.