You're in good shape either way, if you used that machine to generate profit for your business. But if not, then you have to consider that $45k today is actually worth less than $41k in 2021 dollars, due to massive inflation the last two years. Indexes vary, but the average indicates that $41,000 in 2021 would be $46,100 today.
The average return on a CD over this time period is just shy of 17%, so if you had just put that $41k into CDs, you'd have $48k today. Of course, you wouldn't have had that nice tractor to use 3 years in-between.
jyoutz already nailed it, that they're depreciating assets, even if that depreciation comes from inflation alone. If you're generating profit from it, then it's still a good investment, like any piece of capital equipment. For the rest of us, at least they're depreciating far slower than almost anything else we buy.