To be direct you need SEO for a simple reason “not to spend money on ADS” !!!
Google gives this possibility especially to them that want to give value and content for google. From this google start to rank higher your website.
To be clear SEO is a free strategy spending nothing that gives you traffic all the time. If you optimize your website lets say for 5 keywords, this mean that for the coming days weeks even years you will get free traffic from google in continuity.
With time I have understand that SEO traffic has more quality than ads.
Anyway there is a difference that if I spend 1 dollar for a click lets say for the keyword “best digital marketing for 2021” if someone that has not big interest on your website he visit for curiosity and than leave the website but you the same spend that 1 dollar for the click.
In SEO is different clients can click you all the day 100–200 people but you will spend nothing zero on every click they do in your website.
So, this is the particularity of SEO continuous and quality traffic for a long of time spending nothing.
I have created a free tool called SEO ONLINE TOOL where you can see what are the problems and what you need to improve on your website so you can rank higher on SEO.
Hope I give some value!
All the best!