I'm just doing a little survey about what you guys are missing as a service since almost every single idea every single thought is already taken, so why not ask the user himself.
What are you guys missing ?
Because an idea is taken it doesn't mean you could not do it better. Although the less competition you have the better. If you have good idea that is already taken, never mind start working on it. The power is to start working on it and not to think about what you can do and get discouraged because such thing already exists. So far I can't tell you what you could do as I have never brainstormed such thing.
You can maybe start a multi wallet service such as exodus,jaxx,coinomi etc... try to include as much coins as you can. Because I do believe we migh have lack of wallets that support big variety of coins. How can you monotize it? Include exchanges such as changelly,shape shift or yet create your own bots trading bots and offer your own rates and clone services like shapeshift, create your own mixing service and integrate with it. I mean it really depends on your budget, are there any more people helping you out or are you doing it solo etc.
Some easier way to get started is to buy domain+hosting start a blog and try to push it through affiliate links to earn a good revenue. Although it can take time to build it but everything takes time right.