It is not easy to get business partners because you have to show your business plans to get it. There is a chance that their goals are different but if everyone gets along right away they will have a stable business. It is true that having business partners is very helpful because it will increase the capital investment and above all it will be easier to handle the establishment of the business.
What you said is true, I have had two failures in business partnerships. At first I believed because we had known each other for a long time, high school friends, agreed to do business together, agreed to deposit capital into the account, the business was doing quite well and should be profitable after we broke up, but the answer was that there was no money. I checked the account and found that there is. So the conclusion is that just trusting capital is not enough to build a partnership, even though our friendship history is good. As you said, siblings, even husband and wife, let alone best friends, are not necessarily compatible in the partnership business.
Usually a person who likes to fight and doesn't like to complain will not be whiny easily when he stumbles over something while running a business, because he will prefer to stay strong as long as he knows how and still has a path for him to take on his own. Most successful businessmen are businessmen who are not whiny and complaining, even though a small portion is based on inheritance from their parents or continuing their long-running business. But I wouldn't call him a business fighter because people who continue the business from their parents are people who have never felt the bitterness of struggling from the bottom alone.
Of course, if you want to be a successful entrepreneur, you have to change your mindset. So it is important for us to learn and instill in us how important it is to be brave, persistent and creative in achieving success in doing business. Stumbling is a common thing in every business, what is unusual is how we can get up afterwards.