You can have a messy MVP, I always start with some half baked MVP. But if you roll with that as your product you're shooting yourself in the foot a million times down the line. MVP should be the discovery phase and then after you know and understand the problem you should just build the thing from scratch. It saves you a bunch of pain down the road. If it took you 1 or 2 months to build the MVP it will take you half or less that time to recreate it from scratch. You understand the problem completely and most of it will be you just retyping from memory say in data oriented design rather than object oriented. So really there is not too much effort required after you have defined the problem and solution. So yeah, it has nothing to do with ego, it's just a reality of working on projects other people's companies will be relying on.