Assume the people running the other service are geniuses that have tried everything feasible. Figure out why they haven't achieved crazy success. If there is something you can differentiate on with that as the starting point then pursue the idea.
I think this is a really good point. When I was younger, I would probably have told myself that they haven't been successful because they're not smart enough or didn't try hard enough. Now I've been around the block and I think more like they way you're suggesting.