A "me-too" product may be fine when starting and your goal is to gain experience. It may also be fine to enter an under-served niche, where the users are not happy with the currently available products.
But if you enter a popular, saturated niche, you will suffer - you'll spend 95% of your time just catching up with the competitors. You'll spend time building bridges between your product and the competition. You would have to make hard choices whether to innovate or copy from competitor (and thus not forcing user to re-learn what they already knew). If you implement a feature users are requesting and the competitor does not have, people will not switch to your product because you are missing other features or because you have no way of contacting the users or because they are simply loyal to the competitor. You may win in the end, but it will cost you a lot - make sure you have more resources at your disposal than the best competitor has before you start.
But if you enter a popular, saturated niche, you will suffer - you'll spend 95% of your time just catching up with the competitors. You'll spend time building bridges between your product and the competition. You would have to make hard choices whether to innovate or copy from competitor (and thus not forcing user to re-learn what they already knew). If you implement a feature users are requesting and the competitor does not have, people will not switch to your product because you are missing other features or because you have no way of contacting the users or because they are simply loyal to the competitor. You may win in the end, but it will cost you a lot - make sure you have more resources at your disposal than the best competitor has before you start.