After a quick read of the article, it's not measuring how matcho they are, but how competitive they are. Even that is by proxy. Men who have lived with more men will tend towards a game of skill for a larger payout, over a fixed payout.
I personally consider the risk management of being competitive to be an extremely important life skill. Knowing your capabilities requires practise and comparison. Men also tend to change their behaviour patterns when a women is present, particularlyyounger men. "Machoism" is often just our tribal bonding instincts kicking in. It let's young men learn the limits of their own capabilities and the capabilities and temperament of these they are working closely with.
Testosterone spikes inhibit risk assessment. Testosterone spikes based on social circumstance rather than the time of day. When there are smaller males/females around you can dominate, testosterone spikes. When the other males are bigger, stronger and more aggressive, testosterone doesn't spike. Making you avoid conflict instead.
A lack of risk assessment, along with increased impulsivity, is a feature. Useful to get males to initiate fighting.
Testosterone has complex effects. It is also one of the few hormones that significantly changes in the male brain. Learning to both control and utilise its effects is critical to the proper development of a man.
Testosterone changes your risk assessments, rather than jamming them. Uncontrolled, it can be problematic. It takes practice and training to channel that in productive directions. Without that practice, it's effects are either bottled up (with a tendency to explode) or lead to fighting, or crude domineering. Neither is healthy.
I wasn't reading and critiquing the underlying paper, I was primarily checking if the headline and methods matched up. They don't. Confidence and controlled risk taking are very different from "macho".
They also seem to make the correlation ≠ causation fallacy, though that might be fixed in the actual paper. Is it living in a mixed house makes men less confident, or are less confident men more likely to end up in a mixed house?
I'm definitely no more than a reasonably informed layman in sociology. I do have scientific training, however, so can spot the more glaring signs of a journalist going beyond what a paper says, or the data backs up.