You probably won't see this, but I hope you will amend your definition of capitalism:

Capitalism is defined as a set of rules/regulations that allows people to own ~~the~~ capital ~~that they produce.~~

You know this, right? We all know a trust fund baby is perfectly capable of using the wealth they were born into to buy a factory, mine, apartment complex, or shares in all of the above. (Hence profiting off of value they did NOT produce.) We all know capitalism does not distinguish in any way whatsoever between this form of capital ownership and the self-made variety.

"Capital they produce" and "capital they acquire / inherit / use stolen money to purchase" can both be wielded the exact same way. That's the point of capitalism.

And this is only half of why, "that they produce" doesn't work in this definition. The other half is that it contradicts the definition of "capital."

Capital is literally "any form of property that can be used to collect the value of other people's labor." That is the opposite of "ownership over the things you produce."

The exact opposite.

To "own the capital you produce" one must personally build the means of production. Otherwise, the owner is owning the capital someone else produced.

And you'll find the vast, vast, vast majority of almost every form of capital (patents, copyrights, factories, burger machines, server computers, office buildings, mines, mine equipment, oil rigs, oil tankers, power plants, land, the list goes on) does not belong to the people who turned the screws, drew up the plans, welded the seams, mined the materials, performed the research, wrote the movie script, poured the cement, or otherwise PRODUCED the capital.

It belongs instead to the people who funded it. The people who, under capitalism, own it.

Anti-capitalists are not against people owning what they produce. In fact, in America, there is a distinctly anti-capitalist business model that thrives in numerous cities called a "cooperative" (co-op for short) that is owned by either (a) customers, or (b) workers. And a worker co-op is literally workers "owning what they produce", but is considered market socialism by anyone who cares about using words correctly.

I would love if co-ops replaced corporations. Any anti-capitalist would. Even Maoists would tell you, "a society full of co-ops would be wonderful. The only reason I don't find that sufficient is because capitalists would use violence to crush co-ops just as they have used violence to crush governments that didn't favor US corporations."

All anti-capitalists want people to be able to own what they produce. The system that robs people of their control over what they produce is exactly what anti-capitalists have been struggling to overthrow.

(Aside: many anti-capitalists support a "corporate death sentence" where any company that commits a crime causing more damage than it can afford to repair can have its assets seized and turned into a cooperative and given to its workers. This allows a company deemed "too big to fail, because too many workers would lose their jobs" to be kept running and keep its workers employed while also punishing the people whose decisions caused the damage. The investors would lose their shares, and the CEO elected by the investors would lose their job and their shares. Everyone else would be fine.)

Main point: I think before asking,

why do so many people dislike capitalism?

You need to first ask,

how do people define capitalism, and is it possible for the thing I like (people owning what they produce) to be protected in an anti-capitalist organization or system?