What do self-made billionaires say about the biggest mistakes to avoid when building wealth?

Self-made billionaires and multimillionaires in these videos point to several recurring mistakes. The most common is trying to save or work your way to wealth instead of investing; one guest said you can only invest your way there. Many also warn against blowing money after a good month, since the next month may bring less. Getting too comfortable once successful is another, as is being under-financed: one owner said most failed businesses lacked the cash to survive a tough stretch. Athletes and others who spend heavily to match their earnings, keeping the same lifestyle after income drops, are cautioned too. Several guests also warn against heavy leverage, and against putting all your money in one place, with one saying to diversify your wealth so one bad turn doesn't wipe you out.