Why do SSD drives fail?

The main reason SSDs will eventually fail is the fact that NAND flash can only withstand a limited number of read/write cycles. NAND flash is non-volatile memory, meaning it retains data even without a power source. When data is written, the data already stored in the cell must be erased first

I did that. Also, it is better to buy expensive SD cards?

Of course, buying fake or cheap may lead to damaged SSD.