Why didn't Goku use the Genki Dama first?

[GokhanDBZfan]

Against Vegeta, I mean.
If he had stunned him with a Solar Flare and then hit him with a full power Genki Dama, surely it would have lowered Vegeta's power enough for Goku to pull a win without ruining his body with KKX3.

 

[Let's Go Fearless!]

Cuz Kaio Sama told him to use it as a last resort i think, and since Goku was getting excited to fight Vegeta.

 

[Evil Vegeta]

I don't think Vegeta was going to sit there and let him gain power for it.

 

[Jeff Styles]

Goku wanting a good fight against Vegeta and only uses the Genki Dama when he couldn't uses the Kaioken long enough to finish him off.

 

[GokhanDBZfan]

So Goku didn't use it because he was an idiot?

 

[Jeff Styles]

Pretty much. He isn't the sharpest knife in the crayon box.

 

[Let's Go Fearless!]

Just want to support my answer by this scan.

 

[withheldforprivacy]

Genki dama could potentially destroy the planet.

 

[Super Saiyan Overlord1007]

I agree with the Spirit Bomb being a last resort thing. That and his Saiyan blood wanted a good fight. He watched Vegeta waste Nappa (despite him being crippled). He started off fighting Vegeta technically and saw he was just as if not more skilled of a fighter than he was, so he probably wanted to enjoy the fight (Didn't he say he was having fun or getting excited or something along those lines)? He had the upperhand with Kaioken x3 and didn't resort to using the Spirit Bomb until Vegeta became to large of a threat in Oozaru form.

 

[Jerk Store]

Exciting plot?

 

[Let's Go Fearless!]

Last hope.

 

[kriss-]

It was considered a last resort, that and Goku wanted to test his new abilities.