I'm sure that some illegal immigrants do find a way to vote, but it's hard to see this number being remotely close to "millions." There are about 10 million illegal immigrants of voting age; saying that 20% of them are somehow registered and voting seems absurdly high given the risks and restrictions. I could see maybe 1-2% at most going for it.
You'd have to believe that non-citizen voter turnout is at or near levels of citizen Latino turnout (as a share of their total populations). Anybody who knows the first thing about how non-citizens behave with regard to government institutions would find this laughable.
Then, you'd have to have African-American levels of support among non-citizen voters for Clinton just for Trump to break even in the popular vote.
Well there's the figure of about 10 million voting age illegals who were recorded on the census. Now no one knows the total number of illegals in the US but let's suppose that that's a third of the total number of illegals of voting age in the US. If a third of adult illegals in the US were wiling to have their details recorded on the census why is it so implausible to believe that a tenth might be registered to vote and are voting?
Whenever it is easy and low risk for large numbers of people to cheat there will be widespread cheating. No citation is needed for that, that's just human nature all over the world. Therefore in areas where Democrat officials make it easy for illegals to vote and where there are millions of illegals living there will be a significant number voting. I don't know if the estimate of 3 million is close. If you have a better estimate let's hear it.
What you are saying makes sense, but most people here will not believe you. Between voting by mail, which is incredibly open to corruption, and the lack of voter ID, it's quite likely that significant voter fraud occurs. There are also dozens of instances of votes being cast under the names of dead people who were never removed from the voter roles. Many of these cases weren't discovered until several elections after the deceased died, which means there are likely ones out there that simply haven't been caught yet. That's a far cry from millions, but the point is that voter fraud happens and the people dismissing it entirely are being irrational.
The only real reason to fear the implementation of voter ID and other laws to sure up the process is if you think you are benefitting from fraud. After all, Mexico requires voter ID and I don't hear any democrats calling them racist for it.