There are many reasons, safety being the main one, but also the fact people wouldn't understand.
Before I was aware of safety concerns, I told a few friends about Bitcoin and it fell on deaf ears.
I don't do that anymore and pretend I don't know much about Bitcoin when it comes up.
Now, having gone down the rabbit hole, I see problems everywhere to which Bitcoin is the solution. In my mind, Bitcoin is so intertwined with virtually every aspect of life that it's hard for me to relate to my friends. It's like being some sort of secret agent trying to have normie friends.
For example, when a friend gets a job, the most obvious thing to do would be to say "Congratulations! I'm so happy for you!" and I wish I could say that, but that would be as inauthentic as it gets, because what I actually feel is: "What a cruel cosmic joke. This nocoiner loser just got a well-paying job, so he can waste it on expensive restaurants and 5 star hotels." - which of course I won't say. So, instead, I will congratulate him in a half-assed, inauthentic way and run as soon as I can so I don't have to keep up a pretend conversation and a fake smile.
As a result I've distanced myself from my friends. I spend less time with them than ever, and focus on stacking sats to reach my goals. When I work, it is to stack sats. I view my friends more and more as a distraction. I mute them on instant messengers and don't socialize.
If you got into Bitcoin a few years ago and have a nice bag of sats, it's easy for you to say balance is important in life, you have to enjoy yourself too etc., but I got in later and am not in the same place as you.
You were able to build your stack will relatively little effort, little blood lost. To get where you are, or even a fraction of it, it may take me years of chasing the runaway train. I accept that. That's my karma to own up.
I believe Bitcoin will go up forever and it's worth buying at any price, but I have a 'magic', round number in mind that I view as a milestone I want to reach before I can take a breath and relax.
It feels like my life has become one big secret, where I'm not allowed to talk about anything that matters.
I know some of you will say I can introduce people to related ideas, like the broken fiat system, surveillance, Nostr etc., but one thing leads to another. I feel like I have to keep my mouth shut completely, because if I say anything at all, I'll want to spill it all out, just like an alcoholic has to remain completely sober, because a drop of alcohol will lead to a binge. And it's not only the urge on my part, but the fact that my friends will have more questions and I don't have the discipline to lift the veil in small steps and not overwhelm them. Neither do I have the nerves to deal with all the nonsense - fud, brainwashing etc. It's just easier to say "Sorry, I'm busy" and focus on stacking sats.