meaning of "doom somebody"?

Question

To figure out "alternate" vs. "substitute", I went through quite a lot of posts which include Usage of alternate vs alternative with "equally"

doing something is equally alternate to dooming yourself

From the Cambridge Dictionary

doom: to make someone or something certain to do or experience something unpleasant, or to make something bad certain to happen

With the definition above, I don’t really understand the meaning of the quotation.

I googled it but can't get any definition or explanation.

What does that mean? Is it natural to say "doom somebody"?

Answer 1

Yes, it is natural to say "doom someone/something".

From Merriam-Webster

doom verb
doomed; dooming; dooms
Definition of doom (Entry 2 of 2)
transitive verb
1: to give judgment against : CONDEMN
2a: to fix the fate of : DESTINE
felt he was doomed to a life of loneliness
b: to make certain the failure or destruction of
the scandal doomed her chances for election

To put it simply, it means to cause to be sure that bad things will happen.

Many examples use passive voice:

He was doomed to a life of loneliness. (by...?)

That sentence omits the cause, so let's add one in.

He was doomed to a life of loneliness by never leaving his house.

We can easily turn that into using active voice:

Choosing to never leave his house doomed him to a life of loneliness.