As the saying goes... "Failing to plan is planning to fail."
If you want to be successful you must have a plan on how you are going to succeed. Part of making that plan is understanding what the potential points of failure are and how you are going to handle them. It is impossible to do this if you do not understand the business. If you have to react to situations and make snap decisions your risks of making bad decisions increase. This increases your chances of your business failing.
You also need to be able to tell when there are problems with your business. If you do not understand the business, and have little experience with the business, then it will take you longer to recognize that there are problems. The earlier you spot or prevent problems the easier, and less costly, it is to deal with them.
When it can work is when you go in as the silent partner with someone who does know the business. If you watch the show "Shark Tank" you will notice the sharks invest in either business that they know and understand and can help guide the business through the pit falls, or in people they believe in because they just need the money not the partner. None of them say heck neither of us know what I we are doing but lets take a shot together. The reason is there are more fun ways to throw away money than investing your heart, soul, blood and sweat, into learning a business the hard way.
Most people who do learn and build a business with no prior experience actually start from nothing rather than buying a business that has already been built. Of those that succeed big, they teamed up with someone who understood the business side, but they were the power behind the innovation. And most of them got in when there was virtually no competition. Your question does not fit in here.