When I started my project 20 years ago I was as ignorant as anyone else. I knew I was ok at programming and I had done some small games before. Like many I had an idea that a roguelike will probably take couple of years to do... now, 20 years later I'm only slightly better at making a guess when it's going to be ready. This is the "magic" of large scale projects. So many beginners think that if their 7DRL is 10K lines of code, then 100K lines of a bigger roguelike will "obviously" only take 10x more time to complete.
There are couple of ways to react to reality when it hits. Often the moment when you realize the scope of the task is when you have started and are well on the way to create the game engine. At some point it will be clear that it's not 10x, it's closer to like 100x more work. Often people will simply stop there and make up excuses about their real life issues etc. They then proceed to "know" that they would have been able to create the game. The other way is not to give up, but grow up as a person to understand more about the reality of large scale game programming.
People who give up are always going to be bitter about it, but they can't admit the facts, they rather attack real game developers in forums and try to make fun of them when the development is taking realistic amount of time (several years). They can't accept it, because the way they try to prevent a mental breakdown that could follow if they would have to face the reality.