The main point I'm trying to make is that compromising voting machines is not the hard part of rigging an election. It would require a conspiracy so complicated, that I'm not convinced there's any group on earth that could successfully pull it off. Set aside cybersec arguments for a moment:

Let's assume the worst case for security, that there is one machine per state that you can easily compromise to alter election results. This alone is doing a lot of lifting for this example.
Now, you have to cross your fingers and hope that the election is close enough that you can fudge the overall result without raising suspicion
Prior to the election, you have to plan which states to compromise, and what districts you will target for altering votes. You can only really do this in swing states and swing districts. It is usually not clear until very close to the election which places will be optimal.
Because you are at the mercy of RNGesus as for where you can compromise, you have to compromise a lot of extra states ahead of time to eliminate risk that you didn't get enough swingable ones to pull of your plan. This increases head count and creates more liability.
If you swing any given district too far, you can raise suspicion and trigger a recount. If one district raises the alarm, the rest will follow. If you only compromised central machines and not the voting machines and ballots themselves, you fail.
If you can't find enough districts to subtly alter, you fail.
Let's assume you prepared for point 4 and compromised voting machines themselves. This requires massively more people involved, and if only one person gets caught, you fail.
To extend 6. every person involved in your conspiracy is a liability. A single double agent gets in your ranks? Fail. Somebody flakes? Fail. Somebody grows a conscious or gets busted and rats you out? Fail.

While yes, theoretically you could overcome all those obstacles, you'd have to get miraculously lucky and you'd need to not get busted for quite a long time after the election. Why even bother when you can just pay a few bucks to the right people and get news channels to convince the voters to put your guy in charge without committing any voter fraud at all?

Now all that said, I absolutely support improved election security. If nothing else, it will make it much harder to spread FUD about election integrity.