I cant understand this sentece

[mr.vi.et]

Once you actually start looking around, it makes you start to wonder if you would be doing society a favor by getting rid of these people.

I want to know that does "if" in this case begin in a condition clause ?
So where is the main clause ?

I've wondered that perhaps either "you start to wonder" or "it makes you start to wonder" is the main clause? But when looking back, these clause are result of "looking around".

So what does the sentence mean ?

[Clark]

Once you actually start looking around, it makes you start to wonder if you would be doing society a favor by getting rid of these people.

It's a complex sentence with two subordinate clauses.

it makes you start to wonder - main clause
once you actually start looking around - adverbial of time
if you would be doing society a favour by getting rid of these people - object clause.

So, the conjunction 'if' introduces an object clause.