When I think about dealing with customer support, disputes resolutions, get target clients on board and learn about their domain expertise, I'm not that excited. I tell myself well I will hire people to do it, I don't want to get my hands wet with that. Is this a sign that I'm not passionate about it and therefore I will put my start-up at risk? especially if there is already competition.
First to your question. No, unless there is a law in place, nothing is mandatory. That said, not liking your industry will make it more difficult to succeed. Those who love what they do will work harder and longer to achieve success.
But success means different things to different people. Do you need to be rich, or just make a decent living? The lower your threshold of success is, the less you have to invest. Many business owners will choose to make less in order to work less. Others choose to work more to make more. It's all about what your personal goals are.
Finally, there are aspects of every job that people don't like. Those are the things that the business owner can and should hire others to do. There is nothing wrong with that. Again, there are trade-offs. The less you do the less money you, personally make. But it can also help the business run better which can contribute to it's success. Better to have someone better suited for a role performing that role, so long as you can afford it.