Oh yes, just burn all the money so they can use it as a tax write-off?

Does anyone really know how these tax write-offs work? People just use the term without any clear understanding.

Meta like any sane company out there will probably use every rule to avoid (not evade) paying tax. Thats good for the shareholders. But this isn't one such measure, it's mostly R&D expenditure.

It works as a tax free investment. So long as it actually pays off in the future, they get to skip tax by putting it straight into R&D now instead of tomorrow. Another thing they did was sell hardware below cost, so the public kind of benefit - but at the same time FB potentially benefit by undercutting competition and gaining market share... One way of framing that last one might be "Deciding how their tax is spent so that it might benefit Facebook" - from that perspective it doesn't seem like a bad idea (purely from the business side, not public interest) to burn the tax yourself for a little more control.

You cant save money by losing money. Metas tax rate is 17%, write offs are still loses.

Spoken like the average armchair accountant.