1. Should I shut up and watch him continue gambling.
2. Or risk the friendship to fall apart by suggesting him to go to a psychiatrist, because because in my place people who go to a psychiatrist are identical to people who have mental disorders.
I know how that feels, people in my area think that only Schizophrenics, psychopaths, Insanes and the people in similar mental disorder list goes to the psychiatrist while it's not true in reality.
In the USA, if your child has an attention deficit, you should visit a psychiatrist. In my country, if you have attention deficit, that means you are just lazy, untalented, useless. 90% of doctors have no idea what is ADD/ADHD and the rest of 10% think it exists but you have to change your behavior, non medical support available.
So yeah, people lack education and that's why they think so... It's a shame in society... Ahh, that's so bad!
Without a doubt, you should do everything to help him/her and what doesn't depend on you, it won't be your fault.
Btw right now, there are free online resources that can help gambling-addicted persons. There are even Facebook groups where some certified psychologists give a free help hand to similar people.
Betsson even pays some money out of it's pocket to help gambling addicted people. Sounds crazy from casino but yeah, they really do!