Is it safe to cut steel with a miter saw?

I have a small project and I need to cut 3/4" steel square tube. I already own a miter saw, and I don't have the space or otherwise a need for a dedicated tool for cutting metal. I was hoping to just pick up a metal-cutting circular saw blade and use that.

My googling seems to either tell me it will cut like through butter or it will explode in my face and set fire to the house and my wife will leave me and take the kids with her.

You need the right blade and need to go very slowly but, yes.

It can be done with the proper cutting blade/wheel.

Just keep in mind that you aren’t cutting wood so you may need to go slower than you normally would, and I would use a clamp to the hold the work piece.

Might be worthwhile to try some practice cuts as well.

My saw has a built-in clamp, but it's fairly cheap. I'd feel better using a proper clamp for sure.

Take all the safety precautions (clamp it, safety goggles, hearing protection, double condom, mother on speed dial) until you understand how it behaves and use a metal cutting blade. Also use some cutting oil.

Don’t do what I saw one home improvement professional idiot doing - repeatedly slamming the blade into the workpiece until the blade stalls. It was painful to watch.

Oil's a good call that I hadn't seen mentioned yet.

One thing that is overlooked here by the other posts is that the blade speed on a wood miter saw is too fast for the metal cutting blade. If you look at the fein slugger or evolution rages, they operate at lower rpms. It might work but you need to make sure you don't overspeed the blade.

I believe my saw is locked to 5000 rpm.

I know that chop saws and cold saws usually used for metal run a lot slower, but you can buy metal-cutting blades for regular circular saws. I understand that I would have to move very slowly compared to cutting wood, but I can't slow down the blade itself.

Do you have an angle grinder? If you don't need perfectly clean cuts, that might be a better option (and doesn't take as much space)

What you're looking for is a portaband. A hand held tool you can put on a shelf so it doesn't eat up space. Swapping blades lets you use them on wood too.

As for your miter saw, safe is kind of a relevant term. You can do it with the right blade. Personally I wouldn't go past aluminum.

Second this.
Why take the risk of abusing a tool designed for different work when there are readily available cheap tools that are more suitable for the job?

If there's only a few cuts to make you can also just use a (metal cutting) handsaw.
Hand tools are usually the safest option as they give you much more control and sensitivity/feedback than any power tool. The worst that can happen is a skin deep cut or graze, or a broken blade that is easy to replace. You just need to have a bit of time and a bit of patience.

What's wrong with a hack or reciprocating saw?

I don't own one, and I have no use for one outside of this one project. I'm gonna need to do maybe a dozen cuts.

I'm not going to buy one, but I know it's the better option if the choice is there.