If you retire in 30 years, and invest that $50k in the S&P500, you'll end up with about $872k (given the S&P makes about 10% annually[1]). The difference is, in the non-registered scenario, you only pay 50% of the marginal tax rate, because it's capital gains. In the RRSP, you pay full tax on all investment earnings (because it's considered "income" at the time of the withdraw). Your tax bracket might be better at retirement, but will it be 50% better? That's the big question for me (not even considering the value of a liquid vs illiquid investment, but that's more of a personal planning problem).

[1] https://www.investopedia.com/ask/answers/042415/what-average...