"Can I accept money from investors only on the condition that they get paid only after employees and founders get paid a minimum amount, like $1M each?"
Sure, you can do that, but good luck finding an investor who would be willing to actually give you money under those conditions.
If I were an investor, what incentive would I have to take on this additional risk? There are thousands of founders lining up outside my office who are more than willing to accept my standard terms.