Just to be sure, then; your example of $10,000 loss from 2019 trying to "save up to use it" in 2025, means the following:

As long as the current year limit of $3,000 still applies in the upcoming years, your $10,000 loss is "already used up" in 2020 ($3,000), 2021 ($3,000), 2022 ($3,000) and 2023 ($1,000), even if the taxpayer never needs to file taxes in those years, much less, has anything to net it against.