I like the game. It's tiny and simple. I didn't know what to do with it, but then I've realized that it's all about investing and patience.
What this game would need as a challenge would be for example taxes and other things that the player needs to pay monthly and that the balance can go negative which means you need to get a loan from a bank which additionally complicates things.
Various things can be done here, but still, it's a very satisfying game of watching the money just grow and grow and getting richer and richer. I was mashing the A button when I was getting rich. A nice game for relaxation.
One thing I didn't like about the game is how the money numbers and the bitmaps and everything started overlapping one another and I couldn't see a thing. Maybe if you truncated the digits for example when it says $625000, it could be $625K where K means thousand. $1000000 would be $1M. That would shorten the amount of digits on the screen. Also, try using white color to make a rectangle to erase what's on the bottom of the text the game is about to draw. That way the players can see more clearly.
And another thing that disappointed me which was funny was that when I got a facility, I went back to the regular kebab restaurant. What happened? Did I go bankrupt? XD Maybe make a little ending screen with credits saying "As the best Kebab business manager, you became the richest person on the planet and sold your company for a lot of money." and then you choose what you want to spend your money on and you select what you want to buy and see pictures of things like yachts and mansions and planes and other cool things.
Keep up the good work! I'm looking forward to see all of this added into the game :)