Mainly point-3 ^^
3. Mining BITCOIN is done exclusively with dedicated BITCOIN mining hardware based on ASICs -
https://en.wikipedia.org/wiki/Application-specific_integrated_circuit . You CAN NOT meaningfully mine bitcoin today with CPU, GPU or even FPGAs. Bitcoin difficulty adapts to match the amount of mining done on the network and has reached levels trillions of times too high to mine meaningfully with PCs, laptops, tablets, phones, webpages, javascript, GPUs, and even generalized SHA hardware.