Want to turn down a promotion because the manager had an opportunity to promote me before and didn’t. Promoted a junior guy instead.

Long story short they promoted a junior guy a few months ago to a position they think I'm a good fit for now. I busted my ass for an opportunity and made myself number one and didn't get it. I start slacking off and now they want me? You can kick rocks. You had your chance and I'll keep my easy job I can do in my sleep.