Someone who saves and invests $10,000 each year at a 7% interest rate will accumulate $100k in 7.84 years. Out of this $100k, 78% of it will be composed purely of savings. The other 22% will be composed of investment returns.
By the time you reach $900k, $86,000 of the last $100,000 you need to reach $1 million will come from investment returns.
Source: Here’s How Much Investment Returns Matter Based on Net Worth – Four Pillar Freedom