The paid links are good for SEO if you are buying it smartly.
Say if you are buying links from your friends then it's not a problem.
Whereas if you buy from a website which is available publicly then google can find them easily!
In all, I would say, buy links from site where your competitor can't get links...
Paid links can mean links purchased from packages aka directory submission blog posting and etc - those are done with programs like GSA, Scrapebox and such. Those should never be pointed straight at your money site.
IF you want high quality links buy PBN links that are permanent.
Always go for links in your niche
Never get links from sites that have lower metrics than you site
If you found this useful gimme a "like"
If you have any more questions let me know
Paid links works just as @stephenwatson said...
It all boils down to being smart about your purchasing decisions...
Some paid links are really worth it if it can be done discreetly. Moreover if everybody can access and pay for what you want to pay for for, then it's not worth paying for. Trust me, sooner or later, The Google Penalty Team will be knocking at the front of your door
Paid backlinks are not all time bad , like for guest blogging we also pat to the website owner but we provide fresh and quality content it is not bad. But when we negotiate with some websites that we want backlinks by some amount of moneys this is not good. Google dose not like it.