Imagine you got paid one million dollars a year. That's over $2,500 a day. You can work as much or as little as you want, you still get one million dollars every year. No taxes, no strings attached. That's $1,000,000 every year.
After the first year, you have $1,000,000. You're wealthy. With good investments, you could get $50,000 - $100,000 a year in interest and dividends. You probably still work, but you live comfortably. But it's nowhere close to a billion.
After 10 years, you have $10,000,000. You're very wealthy. You can live off of investment income alone. You probably have a personal secretary. And it's still only 1% of a billion.
After 100 years, you would have $100,000,000 dollars. You can talk to A list celebrities and sports stars. You probably have a yacht and multiple large homes. You have multiple staff to manage your day to day life. Now you're at 10% of a billion.
After 500 years, you would have $500,000,000. You're richer than most people. And your only at 1/2 a billion.
After 1,000 years you finally have a billion dollars.
Some people have multiple billions of dollars. Billionaires should not exist.