That was the case in the original Transport Tycoon Deluxe, if memory serves right. Getting cash positive isn't the real challenge, the challenge is growing faster than the competition. Which is a lot more fun if you can play against humans rather than AI. Playing without rival companies is more of a sandbox than anything, where you have to make your own challenges and goals. Can you survive with only buses? Only boats? Make the most optimal rail network? etc. Once you have a grasp of how income is calculated, there are lots of exploits you can do as well to make money practically infinite.
This was also the case for Chris Sawyer's later games too - Roller Coaster Tycoon 1 and 2 challenged you not just with having a cash positive park, but with meeting goals under a time limit or with other restrictions. It is something of a cursed problem in game design for sure - if you make the basic act of surviving too hard, you limit player expression and fun; if you make it too easy, you can just as well remove the money system entirely. I would say the proper balance is one where you can run out of cash, but aren't likely to if you just apply a modicum of business sense. Which is how both TTD and RCT play. SimCity is another example of that. The games are most fun when your own creative ideas have enough breathing room to grow.
Railroad Tycoon 3 ( and 2) achieved a sort of good level of challenge I think. It also seperated personal funds from company funds and had challenges like growing one's personal networth to a certain figure, which involved playing the market. Its business simulation aspects seems well fleshed out.
I used to try to run my company to the ground, buy all the shares for dirt cheap and make it profitable again to become filthy rich. Sometimes it worked, sometimes it backfired really bad, but a lot of fun was had.
This was also the case for Chris Sawyer's later games too - Roller Coaster Tycoon 1 and 2 challenged you not just with having a cash positive park, but with meeting goals under a time limit or with other restrictions. It is something of a cursed problem in game design for sure - if you make the basic act of surviving too hard, you limit player expression and fun; if you make it too easy, you can just as well remove the money system entirely. I would say the proper balance is one where you can run out of cash, but aren't likely to if you just apply a modicum of business sense. Which is how both TTD and RCT play. SimCity is another example of that. The games are most fun when your own creative ideas have enough breathing room to grow.