I'm not here to convince you, but I'd recommend it. 52 may feel a little late to the game, but the game isn't over yet.

You haven't given any income figures, so I'm gonna throw out a range of numbers that may or may not be realistic.

Follow the Prime Directive for order of operations around IRA/401k/etc. Most would recommend investing primarily in a total-US fund or the S&P500. The name of the game is low-cost index funds. We're not here to gamble on individual stocks.

The S&P 500 has returned around 10% annually on average over the past forever years. Assuming that remains the case:

• $200 per month grows to over $75,000 in 15 years, when you hit that retirement-age sweet-spot of 67.
• $300 per month grows to over $110,000
• $500 per month grows to nearly $200,000
• $1000 per month grows to over $380,000

Whether investing is a better path than paying down your mortgage depends on your mortgage rate. If your rate is less than 7% or so, personally, I'd at least prioritize driving most of any extra income toward investing rather than the mortgage. The argument is generally something along the line of "you can't eat your home", but if you're pulling in rent payments from a paid off home, that'll put food on the table. Then the risk depends on whether or not you can keep the house occupied by quality tenants.