How can I get my in-laws to work instead of living off me?

That's your wife's fault for allowing it, and your fault for continuing to prop them up. Sorry, but you should have talked to your wife about this before posting it online. A good woman would never let her husband be used. She'd do whatever it takes to protect him. Your in-laws are pathetic parasites and should bear the consequences of their own laziness. You can't do this for the rest of your life. How is this sustainable?

Before we got married, my wife made it very clear to her family that money would not flow from us to them. At the time it seemed a bit harsh. We're financially fine and I didn't mind helping out once in a while. My mother-in-law is almost 80 and still working. I wanted to make the rest of her life comfortable, so I suggested sending money every month so she could stop working. My wife warned me what would happen, but I didn't listen, and sure enough, as soon as the relatives found out my mother-in-law was receiving money, they rushed in to grab their share. In the end the poor old lady went back to work, and the money we sent went to lazy kids, aunts, cousins, and who knows who else. We eventually had to cut off the money again. It just didn't work.

These folks are already living the dream life: rice + Red Horse, nothing more to wish for 😂

We both work too. Our agreement is that my wife can send her family as much as she wants, and I don't send any. Her income isn't needed for our living expenses. She also pays for entertainment, and I handle the household budget. We use separate bank accounts. We don't talk about money at all. So I never have to hear that some relative stubbed a toe and needs 1500 pesos. She doesn't need to work. It's her choice. She only works to support her family. Money doesn't define my life, so I don't care. Supporting relatives almost always comes with marrying a Filipina. It's a well-known fact, so it shouldn't be a surprise. Decide what amount is reasonable and stick to it. That amount might be zero, but that's between the two of you. Your post doesn't make clear who owns the "family" house, or whether the in-laws are her parents or distant relatives. If my parents had to live in our house, I'd never expect "rent." Would you charge your parents rent for living with you? Try thinking of them as your own flesh and blood rather than your wife's burden, it might help. Funding a business for family almost always fails.