Fast forward 20 years. You were right! You do have a balance of $500,000. But if inflation were also running at 3.6%, the same rate as your investment return, there would be no gain in purchasing power.
In this example, if you want to end up with $500,000 in purchasing power, you would need a nominal return of 7.2% average annual return, after fees and taxes. When you subtract inflation of 3.6%, your real return would be 3.6% average annual return, after fees and taxes. This would be enough to double your purchasing power in 20 years.
The big takeaway here is that if you forget to plan for inflation, you might not be investing assertively enough to reach your goals.
In this example, if you think 3.6% is the annual return you need, you might be tempted to favour income investments over growth investments.
But if you think 7.2% is the annual return you need, you will likely need to favour growth investments over income investments. For example, long-term projected annual returns, based on this year's Projection Assumption Guidelines from FP Canada, are in the range of 6.3% to 7.7% for equity investments and 2.3% to 2.8% for cash and fixed-income investments.