I disagree - high leverage inherently makes systems less stable.

You probably meant to say that practically, high leverage tends to leak into companies of public interest. For example, when high net worth individuals start trimming their private credit holdings, which eventually end up with insurers. That is why the regulators have to watch carefully that it does not happen.

No, I meant that having a lot of debt puts you in a position to be more vulnerable to any kind of negative outcome. Intuitively, this seems to hold true across the spectrum from the personal level to the government level.

If a person has a lot of debt and no savings, and they lose their job, then they will find themselves in trouble a lot faster than someone who owns their home and car and has 6 months in a savings account.

If a company has a lot of debt, they might find themselves in trouble with credit rating agencies as soon as they have a bad quarter. Or they might have cashflow issues if rates increase. Both of these can lead to an accelerating negative feedback loop.

Governments (at least those with fiscal independence) have a unique set of tools to work around this situation, but they too can struggle with high debt loads acting as a drag on future prosperity.

Debt plays a critical societal role in allowing new production in advance of revenues, but it can also be a dangerous trap.

These AI and tech companies are priced as if they are still running a capital-light, 0-marginal-cost SaaS business. That's no longer what's happening. This economic engine makes up a substantial amount of both the value and the growth in the American stock market.

If there's a loss in confidence, high leverage will make things fall faster. This could be infectious. Not just the AI and tech companies, but the whole market might suffer.