Limiting your family size is a lazy, short term solution.

Having a bigger family and teaching them the right values is a much stronger and long term approach.

In a world where the brightest minds are paid to intentionally develop tools to make people betray their values (advertising, propaganda, rolling news, etc), I'm not sure anyone should feel safe about what they teach their kids. Many industries, but especially tech, will do everything possible to make them do whatever makes a few dozen people richer.

The best thing an individual can do against, say, the advertising industry, is to become an important person in an advertising marketplace and then destroy it. You spend 30 years to become CTO at Google and then you set the billing system to charge every customer $1,000,000, right before you drop an EMP in the biggest DC.

Limiting your family size has concrete outcomes, having a big family and hoping you can impart the right values so they go onto have an positive impact is no guaranteed. You can hope your child goes onto develop a fusion reactor that fits in a storage container but the likelyhood is they won't be.

In my opinion it's a way to justify your own (perfectly fine) selfish desire to have a child.

Large family sizes dilute family wealth and leave children at a disadvantage to their better capitalized peers.