In an office of 12, I know at least 5 of them don't need a second job as they own multiple rental houses (so are landlords). 2 of them own more than 2 rental houses.
2 of the others do have second jobs, but that's because they are both saving for a house deposit.
If you need a second income, get solar panels. They can bring in $100s and the income is tax free. :)