Just sold 0.00656btc to my brother's FOMOing friend at $61.5k to buy new tires for my ATV.
Is rubber a good commodity to invest some of my profits in?

Rubber is a good thing to have for an ATV - especially if you want to drive on something other than rims. Last time I checked rims do not get very good traction, they leave for an uncomfortable ride and they are expensive in terms of wear (in the event that you are driving on them).
What I find odd is that alts are doing nothing. ETC is not climbing like this and LTC is at .003 to Bitcoin. It's been .004 all summer and was around .01 last year.
So there is a decoupling here. Odd.
Not odd.
A good thing.. at least while it lasts.
If I sold a piece every time philipma sold a piece, I'd be... well, broke and not bitcoin rich.
Maybe rich, but Bitcoin poor
Few understand what’s more important
will sell another piece based on this advice.
If I sell 0.003 each and every day of the month It comes to 30 x 0.003 = 0.09 a month
If I earn .14 btc a month I am stacking 0.05 a month.
I am fine with this.
Not wanting to be denigrating but could be part of the reason that you are still even thinking about having to stack when you are in your mid-60s as if stacking were to even matter... .. including the fact that there could have likely been more aggressive stacking earlier on..
but hey, you gotta do what you gotta do.. each person has a different situation.
The mine keeps growing and I keep getting more btc in earnings each month.
For sure you have to compete against yourself in terms of what seems to be practical and prudent for you.
Eventually the difficulties will go through the roof but I 3x the size of the mine this year so it works for me and my partners.
Well then you won't be able to stack at all... so merely stacking .05BTC per month does not seem very aggressive.. but hey what do I know about you and your situation.. ?