"We chat" is just to combination of multiple apps. There are many apps with similar concepts like messenger apps. You hardly find any uniqueness in Skype, WhatsApp, Viber and signal etc. but all are successful and have billions of users. They all trying to solve same problem with similar solutions. The only difference you find is UI design and some minor things. Similarly, Udemy, LinkedIn learning, Lynda and Edx offers almost same services. Do we need to find problem or can we solve same problem which is being resolved by competitors?
Your chances of success will be much higher if you do something that other people are already doing successfully because they've proven that people are willing to pay for that service or product. If your idea doesn't solve a problem, then you essentially don't have a market. It's much easier to sell to an existing market than to create a new market because you don't have to spend as much time or money on educating people. Educating people with no guarantee of a sale is an expensive activity.