If you were able to save a million pounds and leave it in the bank, you would receive around £40,000 per year in interest.  This is enough for many people to be able to choose whether they want to work or not.

Of course, accruing £1,000,000 isn't easy, and at a salary of £25,000, would take 40 years, if you paid no tax, had no expenses and never spent a penny!  Most of us are unable to get by without spending any money, so saving £1 million from our normal jobs isn't really an option.