>>213936309
Zenkai boost has a limit, it has to come from real struggle and the stress of battle and can't just be self inflicted on purpose. Vegeta makes krillin shoot him in the chest on purpose so dende can heal him but it doesn't work. Saiyan's can get exponentially stronger by just pushing themselves to the absolute limit with training, Goku knew that and it's why he used gravity training and the time chamber to endure intense conditions and push himself past his limit. And Goku understood power isn't everything and technical skill is more important. Goku also fights for the good of others which pushes him farther than vagetas selfish lust for power ever could.

Vegeta wanted cheap power quickly without earning it and that's why he can never match goku and his work ethic. Even future trunks began to understand gokus methodical approach to developing technique as opposed to vagetas focus on raw power which fucked them both over during the cell saga when their ascended Saiyan forms were too bulky and slow despite their increased power.