I disagree .
Depression and suicide are well researched. While it's true that anyone is susceptible, and I find that statement ("you can't have depression") disgusting! -- it does hurt some people more than others. So I'm on your side;) I just disagree with the title
If you are physically healthy , well-off , have a supportive healthy family -- you're chances of being depressed are extremely lower
compared to other "life situations" . That doesn't mean that it cannot affect you severely even if you have all those things.
It's like seat belts and accidents: wear one and you're less likely to get seriously hurt, but that doesn't guarantee full safety; people wearing seat belts get hurt and die. And saying that statement to you is like going to a disabled person after an accident and saying: "you can't be disabled because you had a seat belt on". It's very offensive, ignorant, and hurtful.
I always say 20/80 is the ratio, majority of suicides are avoidable and caused by distressing life circumstance that
lack support and assistance. (that's what research shows). I wouldn't ignore the other 20%.