Do people actually "grow out" of leftism or is it just a myth created by the right wing so they can call us spotty...

And by caring even more about safety, wealth etc, you give up leftists ideals, and embrace capitalism?. You have it backwards. The only people that "grow out" of it are few leftists that got bribed with big money into joining capitalist oligarchy. The rest is at most too tired from being just wage slaves. Still vote socialist tho.

I hear a lot of people say that they "grew out" of socialism.
Coincidentally they never read any books about it or Communism.

I think some of it is simply misunderstanding the ideologies, initially. I didn't really "get" anarchism or syndicalism until I started busting my ass at a shitty job, and realized that there's nothing childish or simplistic about workers' self management.

Sorry, I didn't mean to imply that socialism was against those things. At least, not in the ultimate sense. But it's hard to deny that if one truly wants to pursue the communist path, they have to be willing to give up political security, close family ties, finances, etc. until the socialist cause is finally completed.

Because let's be honest with ourselves - socialism calls for revolution, often a violent one at that. Even for the most fervent believers, such a prospect is scary. It calls upon the deaths of thousands, and the temporary breakdown of established society. And even if those things weren't guaranteed, even just the idea of radically remaking society can be hard to swallow, since the unknown is always frightening and requires courage and effort to navigate through to the other side.

So I'm not saying that abandoning socialist ideals is the right thing to do, but at the very least it's not hard to see why people might begin to turn away from them, especially in such an apathetic society.

Leftism is not an ideology, it's a diagnosis.

Your mother didn't love you did she?

people changing their mind about things throughout time is a normal thing, some develop a true sense of understanding while some lose their faith. a lot of kids get into leftism because of the aesthetics, and gets bored of it after a while, or to be contrarian, which also changes once the left gain the upper hand as we see nowadays.

how can you think that the left has the "upper hand" nowadays?

It is. It so bloody is, let's not foster self-kidding.

People often do not shed their leftists beliefs over age because they believe the other side is more correct.

They shed them because they realized social change in any significant positive way for mankind is impossible, giving up to cynicism.