There are a lot of misconceptions regarding link relevancy.
The biggest myth is that any link that does is not relevant to the niche of your website won’t help you rank, or hurt your ranking.
This myth has been debunked by Matt Cutts, Google’s former head of web spam.
“In the same way that Google trusts sites less when they link to spammy sites or bad neighborhoods, parts of our system encourage links to good sites.”
– Matt Cutts
Good link building is all about relevant content. A link to a website that has high traffic but is not relevant to your niche might bring in more traffic. But as soon as the user realizes your website is not relevant for them, they’d leave. This would lead to a higher bounce rate.
You need to build links that are natural and sensible. Focus on building natural links and look for trusted and high authority websites that can be linked to your website in a meaningful way. For example, if your website is about health and fitness, you can link it to a high authority website that deals with herbal medicines.
Business always benefits both ways. A good quality link from a trusted website will be helpful for your website and at the same time will benefit the linked website too. You just need to find the relevance.