Energy costs and mining hardware prices tend to fall over time, lowering barriers to entry—especially as some miners exit. Bitcoin incentivizes innovation in energy production and efficiency.
Consider what happens if oil producers stop exporting and instead "sell" their energy to the Bitcoin network via mining. Renewable energy tech will improve and get cheaper and more accessible.
Bitcoin’s economics anticipate most foreseeable problems. No altcoin competes with Bitcoin as a store of value; many altcoins try to skip that stage and aim straight for medium-of-exchange and unit-of-account roles.
Those worried about a shrinking security budget forget the environment will change over decades. Speculative scenarios about how the world will look in 20–30 years ignore dynamic responses.