It could be a 'high variance, low expected value' play. Like pulling the goaly when you are behind. That kind of strategy only makes sense if 'losing by a little' and 'losing by a lot' are equally unacceptable. That doesn't tend to be how economic competition between countries works I think?

if they can decisively finish it fast and keep the spoils. post-WW2 this was only true for the superpowers. and only some of the times. (eg. see the failures in Afghanistan, see how it's impossible to finish a war quickly if there are sufficiently powerful allies of the target willing to sponsor the insurgency/proxy war, etc.)