The author exagerated with the MC being weakly and sick, he should only be in his 30s going for 40 but seems worse, my granpa is 90+ and is healthier han this guy, the jokes are wasted on it.
Unless he was a kid detective in the 70s or he got in a coma and came out of it with his body massively weakened the shit he got is too much.
Only other explanation is a arch rival poisoning him with a cra constitution.
The manga is good, but the MC being the focus of all his bad in the chapter make me cringe, not laugh.