i've long been thinking about the role that kindness plays in our lives, from a seemingly net-zero choice to the benefits it brings both to ourselves and others. I notice kindness is seen as an "extra" in our day-to-day, an energy to dispense as if giving a "tip" once you make sure there's enough in your emotional wallet to do so. What is understated is the dramatic effect that small acts of kindness can have on your own state. I believe the contrary of kindness is also harmful, for your own wellbeing, in ways we tend to overlook.
Let's take the selfless angle; you buy a person food and feel perhaps good about yourself - not just that but you understand that you could have chosen not to do so. In fact, no direct consequence can be observed from either ignoring a homeless person or feeding one. This lack of impact is a concrete variable in the metq-perception of the act. Personally I've observed in the past a compensatory effect from my ego, observing a nagging desire to be seen doing good, not regardless but because of the utter lack of benefit otherwise. At least it'd score me some brownie points. It's this mechanism that can cause people to film their deeds, talk about them, humblebrag or otherwise attempt to showcase their goodness. It's a trap that your mind sets, and can jeopardise the transformative effect of kindness if you indulge it
So if you now see how kindness even in it's simplest form like feeding a homeless person can still be twisted into something self-serving, what then is the benefit once you overcome that hurdle? I believe knowing yourself to do good and practising a genuine indifference to the outcome teaches your brain that you are capable of setting certain boundaries, for your own self, and adhere to them. This practice of boundary setting validates a core of self-respect, and allows you to build a foundation of boundaries, based on this self-respect. In doing this, your mind can trust itself to auto-rely and this provides a sense of trust and further courage to go out there and take risks, focusing on the process itself and not on the outcome. When this happens you can consciously build your relationships, your career, your personal goals free from many constraints like reputation or respect. Because when you trust in yourself, these things will come anyways.
Counter this with the idea of kindness being somehow "weak" and you'll find people who don't respect others and in turn showcase an utter lack of self-respect, and of course self-love.
tl;dr genuine kindness is the key to success