I think it was Heinlein who came up with it, but it's a principle that basic logic dictates is obvious:
Power and Responsibility - those must be 2 sides of the same coin, or very very bad things happen.
The mindset of 'too big to fail', i.e. if things go badly wrong there, government must bail it out for the sake of avoiding seriously deleterious effects on the wider populace, more or less nixes out the responsibility part of the chain there, at least for 'the company' as a whole. At least, the way bailouts have so far been done with banks, which is basically: Give em money, _possibly_ require some sacrifices amongst the board or c-level execs, but the company continues effectively independently.
And, wouldn'tcha know it, bad things happen when you do that.
"Too big to fail" is, to me anyway, all I need to hear. If that's true: Kill that company. Right now. And do a governmental post mortem on how government could have failed so badly as to have just let it happen without writing out laws and regulations to stop it. Too big to fail is a really, really bad thing to ever happen. The only thing that should ever be too big to fail is the government itself. Where there certainly _is_ a balance between power and responsibility: If government fucks up badly enough, very bad things happen to what it represents, namely, the people.
Therefore then, if the consequences are indeed as gigantic as you say they are, then there are only two options:
1. Bite the bullet, split up google, suffer the consequences, and then find ways to break up any other companies that are 'too big to fail', and find out ways to write laws to avoid it from happening again.
2. Government writes some laws to eminent-domain it, so that it becomes part of government, so that bailouts can be done without breaking the balance between power and responbility.
Of course, given the current political climate in the US, that will never happen. But logic dictates that it should.
At any rate: Yeah, it's going to hurt. And it should be done.
Your final 3 paragraphs are missing the mark entirely. They just do not make any logical sense.
If google gets completely asploded by law, you think they all move to apple and apple will turn itself into a monopoly? After it just saw government make a meal out of google? That seems epically stupid, but then a judge just more or less literally called Tim Cook epically stupid for deciding to just flaunt a court judgement, so, sure, let's say Tim Cook did not learn his lesson and remains blind to this. Then.. government will make a meal of apple just the same. Once the first 'tech company too big to fail breaking monopoly laws gets thrown through a meat grinder' has concluded, the meat grinder is built and functional, so (threatening to) toss apple through it is easy at that point, relatively speaking.
I also think you're underestimating the viability of the web and the pernicious brokenness of where we are at today. If google ads just collapses overnight, however will people find stores? That's your argument? That it will simply be impossible to find the online presence of some store or other? I.. doubt that.
A whole company will just disappear because gmail failed? Proton costs 3.50 a seat a month, and that's just to make the point that the most gold plated alternative I know about does not seem like a company killer. Everything google does has an alternative. If a company cannot deal with the fallout of inventorying the services that it uses and making a decision on which alternative to employ plus the costs associated with updating their employees and policies to deal with it, that company was operating on a highly risky precipice already, if the margins are that low. Something was going to unbalance that company and it would fall into the abyss sooner rather than later. Might as well be this.