Well, for starters, Construct 2 is maintained by 2 people, Tom and Ashley. Tom maintains the website with the help of the moderators and Ashley is the sole developer for Construct 2. Whereas, in Unity, whole groups on working on developing and furthering the ability of the game engine. That is probably Unity is so advanced and specializes in 3d gameplay. With that said, it does not mean Construct 2 does not have a chance against Unity. Some construct 2 users are programmers themselves and have been working on 3d plugins for Construct 2. If you search up the Q3D plugin, you will see what I mean.