While I don't use nor know anyone on WhatsApp, I have a few friends that use FB Messenger (which I don't have on my phone) for most of their communication.
Sometimes I get an email along the lines of "X sent you a message on FB Messenger". When I do, I'll jump on the computer, chat a bit, and then remind them "I don't use FB on my phone, so if I'm not near a computer reach me @ XXX-XXX-XXXX or name@example.com". Everyone I'm in contact with has at least a phone number or email address.
Now, I'm 35 so not really in the age group that has 10 group chats, each with 10 people, that have all been going on for many years. You might be in a demographic where that happens more often.
Even so, consider this even though it's not exactly what WhatsApp gives you; it might be useful/healthy to reject the FOMO and half-disconnect (still keeping yourself available, but on fewer services).
Sometimes I get an email along the lines of "X sent you a message on FB Messenger". When I do, I'll jump on the computer, chat a bit, and then remind them "I don't use FB on my phone, so if I'm not near a computer reach me @ XXX-XXX-XXXX or name@example.com". Everyone I'm in contact with has at least a phone number or email address.
Now, I'm 35 so not really in the age group that has 10 group chats, each with 10 people, that have all been going on for many years. You might be in a demographic where that happens more often.
Even so, consider this even though it's not exactly what WhatsApp gives you; it might be useful/healthy to reject the FOMO and half-disconnect (still keeping yourself available, but on fewer services).