Shlomozalman
I will agree that for many couples, specifically the boys who look for and get the rich father in-laws there is no mesiras nefesh involved. However there are a number of couples that both the boy and girl aren’t wealthy and they are moser nefesh for a kollel lifestyle. Be it that the wife has to work very hard to support them (which she does gladly as she appreciates the value of Torah Lishma) and even having to accept hand me downs and clothing from relatives…not splurging…and stam living a simpler life focusing mostly on the spiritual.
This does exist but is by far the minority of the Kollel population in the young newlywed crowd.