Either way, new businesses wont help you with that at all.
Then beat bosses and put the skill points into attack. Problem solved.
I've leveled to 80 in one day and was Tycoon after 3. This was before I had bought any diamonds and before you get a filthy amount of money from fighting.
It's not hard if you are active. And being active is all that matters.
Leveling is a part of the game and you shouldn't be afraid of it.
It's not meant to be possible to stay at a certain level all the time. That's why there are incentives such as better businesses and armory equipment as you get to higher levels.
Camping before you have 1 billion in income is also not very clever. You earn more than 1 billion every hour from the fight list. Just take a calculator and you will find that out. (It's possible to earn much more than that if you mix, obviously, but just as a generic statement, this is correct.)
Why don't you want to level up? The only reason I can think of is taking hit lists.
Why would we need more businesses?
It's easy as shit to get to 1 billion. 2 billion isn't really hard neither, it just takes a bit of time. And if you're not willing to put in a bit of time, then you are not worthy of the income.
The income of high lvl players might become to ridiculous