You are forgetting about supply, if there is no supply of consumers for your products there is no roi.
Unsurprising, as the experience is being degraded. I now get far more spam, see more hateful and unmoderated responses to certain people, and the glitches are increasing. I now open the app less often too.
Maybe that'll reverse, it's too early to say. But it's also wrong to dismiss this as flippantly as you have.
So it's largely pointless to hand-wring about what has been lost for users and advertisers in the past few weeks, as it wasn't working anyway. A dramatic change had to come someday, somehow; whether it be the company going insolvent and being acquired or someone coming in to attempt a dramatic turnaround.
So the latter has happened, and Elon is determined to make it much better for users and advertisers over the long term. Will he succeed? Nobody knows! But the drama of the past few weeks is not any indication either way; it's just inevitable upheaval when a turnaround effort begins.
Nor was there an urgent need for Twitter to have as dramatic a change as you say, as the company had healthy enough revenue and profit growth over the past five years and decent levels of cash on hand.
What we're seeing now is far more severe and consequential than the normal upheaval in a turnaround effort, and it's far beyond anything that the company was contemplating in terms of its own restructuring and refocusing efforts. I also question the claim that Musk is determined to make it 'much better' for users and advertisers, at least in a sense that most users and advertisers would agree with rather than Musk's own flawed views of what matters.
More broadly, the company has been a disappointment from what investors would have hoped for when it listed in 2013, and has been stagnant at best in recent years with no signs of having any idea of how to reinvigorate itself. Yes it may have had cash in the bank and stable usage and advertising revenue, but a company in its position needs to have a clear mission and path of improvement and growth, which it has not had for a long time, if ever since its first few years, really. That cash would start running out with the losses it's been recording lately, and in an increasingly hostile marketplace, raising new funds would have become difficult without solid signs of a bright future.
We can all have our opinions about the merits of what Musk is doing now, but it's all just conjecture and holds little weight until things have played out over a few months and years.
For what it's worth, I'm not any kind of Musk devotee (see other recent comments of mine for more about this); I'm just interested to see how it plays out, and skeptical of people claiming to make long-term predictions based on short-term drama and emotive reporting of it by people who know nothing about building companies.