I think the poster above you was talking about the chances of death from the virus, not simply the chance of infection.
I think it's pretty well established at this point that the case fatality index for children is vastly lower than for older adults, about 0.1% for people under age 29. [1]
And that's counting people who have bothered to get tested. If younger people are getting asymptomatic or minor symptom covid that looks like a cold, then the "true" ifr will be even lower
Infection fatality rates are based on antibody seroprevalence studies and thus accounts for asymptomatic cases. What you're thinking of is the case fatality rate, not the infection fatality rate.
Seroprevalence studies have been conducted all over the world. For example in Delhi India approximately 50-60% of the population now have antibodies for SARS-CoV-2. There are statistical techniques for adjusting the raw results based on population demographics.
Note that seroprevalence studies will underestimate the number of infections because some recovered patients don't produce detectible levels of antibodies.
I think it's pretty well established at this point that the case fatality index for children is vastly lower than for older adults, about 0.1% for people under age 29. [1]
1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7518649/