Dds father hasn't ever paid a penny, despite being a relatively high earner. Dd is now 14, and over the years there have been various reasons, including being self employed, pretending to be disabled, cash in hand, moving quickly etc. The real reason imo is that he is a sociopath, and initially at least it was a way to still get at me when his previous abusive behaviour was no longer a way to harm me. Luckily he doesn't see her so he can't mess her about emotionally.
I'm average salary, just above tax credit entitlement and having been in poverty when she was little I'm good at making it stretch, and for various other reasons dd has a quality of life better than some dc from homes with twice my income. But that's not what bothers me.
What hurts is the fact he couldn't give a fuck whether dd is provided for or not, and knowing that sooner or later, probably when/ if dd has her own dc she'll realise just how worthless he considers her. And to a lesser extent that if he'd paid, dd could have had the same lifestyle and more than enough in the bank to put her through uni and a sizeable house deposit. Not to mention some of the bleaker times when she was little wouldn't have happened.
I've also been out with two people who paid legal minimum through csa. The first did so because his ex spent the 50% of his salary he originally paid on herself, and he couldn't afford to pay all her rent, bills, and everything for the dc from the half he kept. So he paid her the legal minimum, and then paid all her bills, food shopping, everything for dc as voluntary on top. As well as having dc 70/80% of the time.
Second person initially said he had dc half the time, and split all extras. In reality he saw himself as the hero for occasionally 'babysitting' whilst she went out. To work. And paid the minimum late and with arrears. His ex and I became good friends as are our dc who we introduced after I'd split with him and his ex and I got friendly.