It's about the long term not the short term.
Forcing Australia and other Western countries to face the reality of their circumstances and shaking them out of complacency.
Short term it's all pain but that goes for anything worthwhile. At the personal level well exercise, study or investment are always a negative in the short term. But if you don't do them then a point comes where you'll wish you had.
In Australia's case we've been coasting for decades, our entire economic base has become dependent on selling off finite resources, running up debt and pretending it's all OK.
The consequences of that aren't just in terms of defence but it's ruining a generation also. Lack of challenging work and opportunity, especially for men, meanwhile they've no prospect of home ownership. We're paying a hell of a price for coasting.
Now I don't agree with the detail of how Trump's going about it, and suffice to say I've had personal experience with someone remarkably similar in attitude so I can relate more than I'd like to, but it is shaking things up. It'll almost certainly force change here in Australia.
The reason a nation needs industrial capability isn't just about economics although that is certainly one reason. Australia's present approach of exporting ever more coal, gas and iron ore to fund the import of pretty much everything else is ultimately unsustainable. It's living off capital since those are finite resources which, particularly in the case of gas, are being extracted at an alarming rate.
It's also about defence on both sides of the coin.
One side is about self-sufficiency and not being so dependent on others especially for critical things like fuel, metals, building materials, basic machinery parts (eg bearings), etc.
The other side is that to have manufacturing and heavy industry you need a few things to go with that and this is the critical bit. Among other things as a country you need logistics, you need broad based engineering and scientific capability, you need skilled trades and labour, you need machinery and buildings, you need energy, etc.
In other words, having a lot of factories forces you to have things that are also critical to defence. Because even if they're not in the Army and have never had anything to with it, there's a definite benefit to the nation in having people who can do things and having the machinery and basic materials (eg steel) to do them with along with things like well developed freight movement and so on. If push comes to shove, that stuff has huge value for national defence.
So the negative of Trump is outright chaos and a lot of babies being hurled out the window along with the bathwater. I don't agree with the detail of how he's going about it at all.
But the positive is shaking Australia and the rest of the West out of complacency. Forcing us to face reality that being China's coal mine and flipping houses really isn't leading us anywhere good in the long run.
Trump's akin to the parent who tells their adult kids they're selling the house and moving interstate. In doing so shaking the kids into action that they'd better get their life together, that there's no option not to.