Why the stigma with age gap relationships. Do you agree

I have been with my husband who is a lot older than me for nine years. Incase you are wondering I’m 39 he is 78 yet I think a lot of society does not agree with this type of relationships. We still get a lot of verbal,abuse especially me and often accused of being a gold digger or even his whore but I’m not ashamed to be with him and we always hold hands in public
I’m not sure what the problem is we are both happy and it’s not harming anyone so why the stigma with these relationships?