does it worth nowadays to be sea navigator ?

Answer 1

yes

Answer 2

Still one of the better payed jobs aboard ships, and needed on all seagoing vessels.
But hours are long, there are only a few people per ship.
Wages have gone down compared with jobs on land.
And it is a lot of learning.

So if you want to do it, do, it is worth it.
But if you are in doubt, talk with people who are and people who have been navigator at sea.