[lm28469]

> you can write off the expenses of the video card.

As a random person who buys a graphic card to mine coin you can deduct the card price ?

[bombcar]

Only if you are a "business" and using it for business purposes. And the IRS has all sorts of things to detect a hobby vs a business - https://www.irs.gov/newsroom/earning-side-income-is-it-a-hob...

So for example if you build a workshop in your garage and start making fine wood items, even if you sell them it may not be a business, and count as a hobby.

Usually the IRS is trying to find people with "perpetually money-losing businesses that are deducting each year" but you could get caught up in some cases.