Political content and conspiracy theory follow. This answer is unlikely to be accepted since the OP has gone dark. Nevertheless, I post for reasons that will be explained at the end of the post.
These people are
the citizens of the People's Republic of China and they believe the policies and propaganda of the Communist Party of China.
Some people come to me all the time
If they express themselves well enough
They might get what they're looking for
People, or rather businesses, set up shop in China all the time and if they do not anger the Party they just might get the profit they are looking for.
I fight against experts
I should be sending them gifts
And thank-you letters
The experts are the US-Europe with which China is locked in ideological conflict. However, the hegemon of the East should be "thankful" to its rivals West for providing investment and markets that paved the way for its rise.
Every now and then I have some insights
Not all of them see the light
I remember having one in a leap year
It was bigger than the last of it's kind
These people believe in strange things, right?
Xi Jinping Thought, now an official doctrine of the Party, was gradually developed from 2012 (a leap year). It was affirmed by the Party in 2017 making Xi join the ranks of titans Mao and Deng.
1. China is welcoming of some ideas (intellectual property) and hostile to others (liberal, democratic ideals).
2. Being used primarily by English speakers, the natural Arch-Enemy of the reader is China.
3. Chinese exceptionalism is a branch of Chinese political theory.
4. Might be a reference to the Chinese social norm of having dogs as part of the diet.
5. CH 22-03-09 could be a reference to the 93 Tibetan monks attacking a Chinese police station in March 22, 2009.
Are they gone? Okay, I think the CPC agents are no longer here.
If you are willing to know the truth, do so knowing that I cannot guarantee you or your loved ones' safety.
You have been warned.
TIN-FOIL HAT ALERT:
The OP is a citizen of the PRC and is critical of the government. He found a way through the Great Firewall to post this riddle as his personal protest and let the world know that voices yearning for freedom lie beyond the bamboo curtain. Despite his best efforts though, he was soon found out by Chinese thought-crime police. His account in PSE has since been disabled and his current whereabouts unknown.
However, the flame of user60411's dissent shall not vanish along with him. I post this answer in solidarity with user60411 and all the userXXXX's of the world who believe that Stack Exchange content should be regulated by community moderators and not government censors.
We will never forget.