> Also, respect the team. Maybe they aren't doing what you would, but they are keeping this beast alive, and probably have invaluable knowledge of how to do so. Don't come in pushing for change...

Yes, 3 people creating a revenue of $20 million/year is impressive.

But what if 1, let alone 2 of them quit and/or fall ill? That's way too much risk for this type of revenue.

If a new team member needs a year to just understand how the code is organized, then a well structured and documented rewrite certainly is necessary.