I don't know if its hard to be successful.
The definition of success could simply be doing things others do not want to.
Most definitions of success are always associated with the amount of wealth, how many companies are being run, how many cars and houses they have. The general definition and often people mention, but some people forget that the definition of success is not only limited to things like that.
-Warren Buffett did long term value investing, others did not want to. Other investors focused on fast money and short term gains with higher risk. Which is why Buffett ended up one of the wealthiest, while short term investors couldn't hope to match his success.
Everyone is different in setting investment concepts and not everyone will get wealth from what they plan to do, many people experience ups and downs in building a business or investment.
-Bill Gates did nerdy PC development people avoided. No one foresaw the computing industry and silicon valley blowing up to become household trends. Culturally, it was all about being the quarterback on the football team. Being a geek or a nerd was thought to hold little future promise, much less wealth.
This human being is able to see opportunities in the future, thus setting the standard in developing Microsoft Corporation. At this time, almost no one does not have their product at home, because with the times the need to use Microsoft is getting bigger.
-Elon Musk built electric cars that conventional automakers decided not to build for decades. No one wanted to build an electric car, no one thought they had a future.
Everyone has big plans in life, some people are busy planning but not implemented, Elon Musk is a businessman and owns several companies and currently he has also acquired Twitter and the Indonesian local stock exchange Tokocrypto. Successful people always live in risk and feel comfortable enjoying the risk.
It takes time and effort to develop knowledge, skill and value. Most simply do not want to do it. The path along things people do not want to do, is however often aligned with progress.
The main concept of courage, persistence, skill and consistency!!!
Everyone has knowledge in running something, because this field can be learned if someone has the desire. The three people you gave the example of above were people who took risks, so a few failures didn't stop them from moving on.
This ability is not possessed by many people, so when some failures will make them stop, knowledge can basically be learned according to the abilities we have, unfortunately many people are too afraid to get out of their comfort zone.