I work in the FMCG industry, and we treat supply is effectively unlimited. You will constantly have suppliers begging you to buy more, and to buy new products as they expand their range.

However, as a trader, you will only ever buy what you expect to be able to sell. It would be pointless stocking up on goods which you aren't going to sell, especially in FMCG where you need to sell them before they go out of date, else you lose all of the money on your purchase. Sales are almost always the constraint under normal operation.

Suppliers are attempting to create new demand by creating new markets. They usually offer freebies or discounts for new products in order to gain penetration, but it is then up to the market to decide whether that demand warrants them to continue producing the good. Without demand, they cannot continue to produce, because it would be a loss making endeavour.

Electricity can be seen under the same lens. Like FMCG, it loses value with time rapidly, because it gets lost as heat through storage, and it also costs to store. An electricity producer is never going to create more than they expect that they can sell. They might produce a bit more than actual demand as the means to try and capture new markets for greater long-term profits. Mining is part of this - if they can capture a new market for bitcoin mining, they will generate profit in the long term by continuing to supply that demand.