'One of the biggest contributors to climate change' - this is so far from being even remotely true
You should of course make your own judgments, but many people do not consider that a good tradeoff.
Out of total energy production that's closer to 0.07% (~170,000 TWh in 2019 https://ourworldindata.org/grapher/global-energy-substitutio...).
Unlike actual people mining farms can be placed right next to power source so it's easier to use Nuclear / Wind / Solar / Hydro for such purposes.
While electricity transportation is an issue, it's not a huge one compared to the likes of storage and actually having something generating electricity. And, as it turns out, a lot of the mining farms just use coal (https://decrypt.co/43848/why-bitcoin-miners-dont-use-more-re...), with only around 40% of the energy coming from renewables. Even if they were only using renewables, it's still not zero carbon, since renewables also need to be built & since the total power consumption is increased, older coal plants might be used for longer.
For something, where the economic value is comparatively low.
That's 0.1% of total CO2 emissions per year (https://ourworldindata.org/grapher/annual-co-emissions-by-re...) and 0.074% of global CO2eq (https://ourworldindata.org/emissions-by-sector).
I'd probably agree that this is still pretty high for what amount to digital hording.
On the other hand the seccond most popular blockchain Ethereum is estimated at half the energy consumption (https://digiconomist.net/ethereum-energy-consumption), has a plan to move to proof of stake and has a lot more economic value.
The space is still new and bitcoin has first mover's advantage, name recognition and trust (most hashrate, most reviewed codebase, etc).