File for divorce, which is not in and of itself a problem
Agreed; there's nothing wrong with either partner filing for divorce if they want out of the marriage.
File for "Spousal Support"
This seems to be far more prevalent in the US than up here in Canada. Also, spousal support is somewhat based on the income of each spouse, but I do agree that it is largely stacked against men. But, if you get a good divorce lawyer, your chances of having to pay spousal support are slim to none.
Because women almost always marry above their financial status
You got a source for that?
She can leave the man over something as simple as "I'm bored and it's not exciting anymore".
This brings us back to my original point of making sure that you really know who you're sharing you life with before popping a ring on her finger. If your wife is going to end a marriage as flippantly as that, I can guarantee you that there will be signs of your impending doom long before the wedding.
If you lose your job and fall behind on payments, you're a "Deadbeat Dad", but if she does the same, the Judge will tell you that "You just need to cut her a break (For the 15th time) and let her get back on her feet (Which she's been trying to do for 9 months+, even as she buys name-brand purses)."
Yeah, this aspect is pretty shitty for guys. However, if you get custody of the kids, you'll be fine. Keep in mind that the courts do take the kids point of view into consideration. If the kids say they want to live with their dad instead of their mom, the courts will almost always let the kids live with their dad.
you can raise a family perfectly normally without involving the government in a legal contract
Oh, of course. I don't dispute that. However, there are benefits that come with marriage. Among them are several tax breaks which can be enormously important to low-income families; medical benefits, like if you get put on life support and you're in constant suffering, you can give your spouse permission to have the doctors pull the plug, or let her give the order to keep you alive. Then there's also the matter of work benefits. If your job has a great dental plan or something, you can't share it with a girlfriend. However, you can (in almost every case in Canada) share it with a spouse and kids.
Once again, this really all comes down to making sure you know who you're getting into a relationship with before you get married. If your wife is evil enough to do all of the things you listed, do you honestly believe that simply not marrying her will somehow turn her into an entirely nice and pleasant person? HELL NO! If your spouse divorces you for no reason, gets spousal support and child support and destroys your life with those, you can bet your ass that she'd find other ways to milk you dry even if you didn't marry her.