Since there is an obvious barrier of entry for anyone trying to beat you once you’re established, you won’t have to worry about having competitors “buying” their way to the top. Their only option is pay per click ads, but then again, it isn’t the same as getting a higher position on the SERPs. Again, this is assuming that you took the right steps and were patient enough to solidify your place in the top search results. 
The challange is for SEO's then to tell this to the clients and not worry of loosing them. What to report on then, for GMB- impressions (this should decrease because I found on the maps that the link to website isn't always there!), GMB dashboard for views (a test showed stats on the GMB dashboard are incorrect) the suggested channels social, youtube don't fall under organic traffic

The term is intuitive; the definition of organic marketing refers to the act of getting your customers to come to you naturally over time, rather than ‘artificially’ via paid links or boosted posts. It includes any direct, instinctive, and , with the exception of paid marketing tools. Paid tools, such as artificial paid link-ads, are considered inorganic marketing. If you’ve been putting your blood, sweat and tears into revising and reinventing your user interface, maintaining Twitter and Facebook accounts, building your email lists, and improving your SEO, you’re doing it already. Now, let’s take a closer look at why it’s effective, and how you can do it better.

So, closely monitor and analyze all yours, and your competitor’s social marketing activities. Find the kind of posts your followers and target audience find interesting by analyzing social channels, campaigns and posts.  Figure out what works best for your brand in a given scenario. Based on the inputs you gain from analyzing your social channels, craft the social media marketing strategies for your company.

There are many reasons explaining why advertisers choose the SEM strategy. First, creating a SEM account is easy and can build traffic quickly based on the degree of competition. The shopper who uses the search engine to find information tends to trust and focus on the links showed in the results pages. However, a large number of online sellers do not buy search engine optimization to obtain higher ranking lists of search results, but prefer paid links. A growing number of online publishers are allowing search engines such as Google to crawl content on their pages and place relevant ads on it.[16] From an online seller's point of view, this is an extension of the payment settlement and an additional incentive to invest in paid advertising projects. Therefore, it is virtually impossible for advertisers with limited budgets to maintain the highest rankings in the increasingly competitive search market.
Check out the average CPC for some top industries. These are the costs of one click. Mind you, that’s a click that is not guaranteed to convert a customer. With paid campaigns, you have to keep optimizing and testing the ad creative to lower your CPC and increase your CTR. You can imagine that it takes a massive budget to even set a paid campaign in motion. And it requires just as much to keep maintaining it.
Remember when you used to rely solely on search engines for traffic? Remember when you worked on SEO and lived and died by your placement in Google? Were you #1? Assured success. Well, okay, maybe not assured. Success only came if the keywords were relevant to your site users, but it was the only real roadmap to generating site traffic and revenue.