I strongly disagree with your second point. There are quite a few very successful entrepreneurs who have started companies while being mired in terrible financial circumstances. In fact, it's very common for these circumstances to be the stimulus that gets people moving in the direction of their own company. There are many, many stories of this, to the point that it's a cliché.

I myself started my first business at a time when I had virtually no money in the bank, and my car was literally repossessed one month before my business became profitable. If I had stopped and said "I can't afford this" and just given up and gone to get a job, I would have never seen the success that came later.

Also, you point out particular entrepreneurs who came from rich families. You completely leave out the wide array of entrepreneurs who did not. John Paul DeJoria, for example, was living on a friend's property because he was homeless and had almost no money. He started his business in those circumstances. He's estimated at somewhere in the ballpark of 3 billion net worth presently. There are quite a few stories of people with virtually no money building empires out of the rubble.

While I agree that there are a number of factors that feed into whether a startup is successful or not, I would kindly submit to you that one's attitude towards whether or not it can be accomplished is a very massive part of the picture. It takes focus and determination to get most businesses off the ground. Once you begin listing the reasons you can't accomplish it, you've begun setting up the circumstances such that you won't.