This is not the case. Research it yourself:
"Evidence is emerging that people get better protection by being fully vaccinated compared with having had COVID-19. One study showed that unvaccinated people who already had COVID-19 are more than 2 times as likely than fully vaccinated people to get COVID-19 again." https://www.cdc.gov/coronavirus/2019-ncov/vaccines/faq.html
https://www.cdc.gov/mmwr/volumes/70/wr/mm7032e1.htm?s_cid=mm...
https://www.usatoday.com/story/news/health/2021/08/09/covid-...
https://www.healthline.com/health-news/people-whove-had-covi...