Not a hostile question, I'm genuinely trying to understand this: How is liquidity provided by, for example, someone interjecting themselves into a trade that was already going to happen?
If you place an ask and the price moves down it might not fill, so you have to move it over time while the price slips.
People provide liquidity by seeing your new sell order and filling it quickly, or by leaving a large number sell orders that people can take immediately, which results in money moving more quickly and consistently.