In addition to what others have already said (McD paying above minimum wage), only you paying more leads to the following:

• your competitors gain an advantage as they have lower labor cost
• only a tiny fraction of your customers have more disposable income because the rest of the population is unaffected
• and even then, for that tiny fraction, you’d have made more money if you hadn’t paid it to them in the first place, because they’re not spending it all on you, and also taxes

So for them, they need to make sure their competitors pay more money to their employees.

Also, their food is garbage, you’re doing yourself a favor not eating there.