[imtringued]

Assuming 5% inflation with 0% returns for 50 years and a 20% capital gains tax $1 turns into $11.47, a rise by $10.47, therefore you owe $2.09 in taxes. $11.47-$2.09 = $9.37.

You rightfully expect $11.47 but you instead get $9.37 after taxes. Your wealth has shrunk to 81.6% of its original value, meaning you need to net a return of 22.4% over 50 years to break even, which is equivalent to a 0.4% gain every single year or a 0.4% loss every single year.

If you could find a 4.7% interest savings account you would beat the perfect savings vehicle.

In practice inflation is laughably low right now. With current inflation (2.5% yes it's an overestimate) you would lose 14% of your savings over 50 years.

You're right that this is forcing you to take on more risk, but not substantially. You may need to put 10% of your money into the least risky stocks and keep 90% in a risk free asset.