Two reasons, I'd say. First, previous panics mostly were that. After a year or two and the heavens didn't fall because a particular individual had been re-elected as US president, then things went back to something like normal for the next several years.
More important, anything that involves manufacturing explosives is highly regulated, attracts lots of public and media attention and usually opposition. Frequently from the eco zealots too as traditionally many of these processes were highly polluting and the fact they're not now is of little matter to people who simply ignore facts that don't support their prejudices. Take the old Australian government powder plant in Mulwala, New South Wales created in a rush during WW2 and which was a terrible polluter that damaged the ecology of a whole river basin. Around 15 years ago, that obsolete facility was set to close without major, major investment and its new owners Thales /ADI, part of a multinational, went to the Aussie government with a plan to replace it with a state of the art factory funded 50/50 by Thales and the government. Most governments would have rejected the proposal, mine in the UK undoubtedly would, especially as the eco-warriors assisted by the media created a sh*t storm and got up lots of public opposition. Fortunately for Thales - and us as handloaders and shooters - the government thought strategically both in terms of export earnings and for national security in a region where Chinese power was becoming more aggressive. The Greens opposed the process at every stage and continue to do so now over explosives being trucked through towns to the dockside. If that project hadn't got off the ground, there'd be no Hodgdon Extreme grades or IMR Trail Boss and 8208-XBR because that's who makes them.
And that experience raises an important point. Smallarms ammunition components no longer loom large as major factors in modern military thinking or politicians' perceptions of security issues. They're not sexy like Javelin missiles or F-35 joint strike fighters, and we all know it's the latter that win wars these days. Yes so, but I wonder how well Ukraine would be doing right now if it ran out of rifle and machine gun ammunition even if it still had drones and Javelins. Both are important. Governments no longer see it that way and will no longer pay for security reserve capacity. (When Kynoch closed late last century, that was the sole manufacturer of 50BMG ammo in the UK, but HMG wouldn't pay for or even part-subsidise a modest factory and pile of secondhand machinery which was then sold off to a Greek company.) Hell, the private owners are big rich private companies, aren't they? That may or may not be so and even if they are rich they got that way by investing for guaranteed sales and profits, not by operating loss-making charitable operations.
Expanding existing explosives manufacturing operations, even more so a greenfield build is a long-term and expensive process before you get the first penny of return back. It's also a fairly small sector in the West these days, but relies on a small pool of people with specialised safety, technical and production skills. Even if a corporation can throw the buildings and storage bunkers up, it then has to poach and/or train up specialists, and teams may take a year or two to gel and get in the groove. Before you spend the megabucks and assign part of your management resources to plan and project manage such a new venture, you've got to be sure you're going to sell enough of the output to make a profit (and cover the build and setting-up outlays) at the end of whatever timescale it takes to get into full production.
So, who on this forum can guarantee the demand (and high prices) will still be there to make a profit in producing primers, powders and ammunition in three, four, five years time? A silver lining of Putin's Ukraine 'Special Operation' (Invasion? What us? No never!) might be if Western governments and their advisers wake up and recognise that the world is again a dangerous place and that predators will seek out and exploit weaknesses in the 'soft democracies', because without a doubt western nations' smallarms ammunition manufacturing is one such.