This quote is brought up often but it should be taken with some skepticism. As user GatorD42 pointed out when this was brought up before:

...Baum claims Ehrlichman said that to him in 1994 while he was researching for a book he published in 1996 about the drug war. He didn't include the quote in that book, but instead published it in 2012 and again in 2016, after Ehrlichman had died (in 1999).

This is a very explosive quote - if Baum had included it in his book in 1996 I am sure it would have garnered a huge amount of attention for the book. Instead Baum did not include it in his book, but instead would wait for decades later when Ehrlichman was no longer around to dispute the quote.

At any rate, if the quote was actually said by Ehrlichman, it isn't a very accurate description of the drug polices of the Nixon administration. While Nixon is remembered for "war on drugs" rhetoric, the actual substance of his policies seem to be different than what people think it was:

...I have been fortunate over the years to discuss the distorted memory of Nixon's drug policies with almost all of his key advisors as well as with historians. Their consensus is that because he was dramatically expanding the U.S. treatment system (by 350% in just 18 months!) and cutting criminal penalties, he had to reassure his right wing that he hadn’t gone soft. So he laid on some of the toughest anti-drug rhetoric in history, including making a White House speech declaring a “war on drugs” and calling drugs “public enemy number one”. It worked so well as cover that many people remember that “tough” press event and forget that what Nixon did at it was introduce not a general or a cop or a preacher to be his drug policy chief but…a medical doctor (Jerry Jaffe, a sweet, bookish man who had longish hair and sideburns and often wore the Mickey Mouse tie his kids had given him).

https://www.samefacts.com/who-started-the-war-on-drugs/

..."Enforcement must be coupled with a rational approach to the reclamation of the drug user himself," Nixon told Congress in 1971. "We must rehabilitate the drug user if we are to eliminate drug abuse and all the antisocial activities that flow from drug abuse." >The numbers back this up. According to the federal government's budget numbers for anti-drug programs, the "demand" side of the war on drugs (treatment, education, and prevention) consistently got more funding during Nixon's time in office (1969 to 1974) than the "supply" side (law enforcement and interdiction).

Historically, this is a commitment for treating drugs as a public health issue that the federal government has not replicated since the 1970s. (Although President Barack Obama's budget proposal would, for the first time in decades, put a majority of anti-drug spending on the demand side once again.) ...

https://www.vox.com/2016/3/29/11325750/nixon-war-on-drugs

You can also observe this in the opposite form: how hard it is to get laws that people want but special interests oppose.

Current example: many individuals are trying to get access to their health records through APIs but the makers of Electronic Medical Records are fighting tooth and nail against it, with FUD. Because they want to keep their lockdown on our data.

To this day there are people that support it, as long as it's for other people.

Even here on HN where the audience is ostensibly more enlightened you'll see comments along the lines of "sure legalize cannabis and mdma, but let's not do so with the dangerous drugs like meth and heroin".

That thought is part of the "protecting us from ourselves" lie, and it is well intentioned at that point but it certainly doesn't help anybody.

Sometimes looking back on these things it is very difficult to determine motivations and the players. This isn't one of those times though, what it was "about" is pretty well understood.

As for popular support, racism probably played at least a comparable part to the abstract "protecting people".

The more I learn about the history of the War on Drugs, the more horrified I get. Sure, drug abuse is a serious problem in society, but the same goes for a lot of similar problems like compulsive gambling, sex addiction, anorexia, and a long list of other issues. Yet the political response to these other problems is very different.

American Prison by Shane Bauer

A good read.

Fixed. Thanks!