I'm not arguing that these factors are large enough to change the answer, but other ways someone can be a net drain include

a) being criminals who inflict various kinds of harm on others

b) working in jobs that would otherwise be taken by existing locals, who are now displaced onto benefits

c) working in jobs that would otherwise not be able to find employees, thus asserting downward pressure on wages/conditions

d) using those benefits which are available, such as (in the US) public schools, emergency departments, and sometimes state-specific benefits

e) using resources from a finite pool such as e.g land in a farming county, houses in a city that refuses to allow further development

Most of these arguments can be found when people are objecting to legal immigration

I think you may be labouring under the burden of prejudice.

No, he's pretty much right. As an illegal immigrant, I still have to pay all kinds of taxes, but it's really hard and sometimes dangerous to access many of the public services those taxes provide. Public goods like roads, street lights, and the fact that armed robbers find it more convenient to leave me alive instead of dead, those I can benefit from. But I'm reluctant to report crimes to the police, I had a hell of a time getting a covid vaccination, and I'm not going to get any retirement money from the government when I'm too senile to work. At least I can still audit classes at the university.

I'm not much of an "agitator on one of the sides". I can't afford to be an agitator, I might get deported. I'm just telling you what my life is like.

As we all are.