Yes, it's generally OK to not wish everyone a happy birthday; it largely depends on your relationship with the person.
If you have a close relationship with someone – family, close friend, or colleague – wishing them a happy birthday is generally expected and appreciated. It shows you care and remember their special day.
However, if you aren't close to someone, and they're not close to you, you shouldn't feel obligated to say anything. For example, if it's an internet friend you rarely interact with, or an acquaintance you haven't spoken to in years, it's perfectly acceptable to skip the birthday greeting. Forcing a greeting in such a situation could even come across as insincere.
The key is to consider the nature and strength of your relationship with the person. Don't feel pressured to extend birthday wishes to everyone you've ever met; focus on those with whom you have a meaningful connection.
