Try to do any task on a computer and you'll find 95% of existing things suck and can be improved. You can sell these improvements. Don't worry about competition, that just means your idea has been validated. Make stuff you want to use yourself, that way even if you fail to sell to others, you're not at a complete loss. Plus you do not need to repeatedly iterate with a customer if you are the customer.

To add to this, the bigger the improvement you offer, the easier it is to sell.

Selling a 10% improvement it hard, selling a 10x improvement is much easier...

This is where some acknowledgement of the fact a lot of low hanging fruit has been eaten at this point is in order. I feel like more game changing products of this decade are not going to be Uber for X type apps but more original creations.