Does it make sense to invest in SEO as a competitive, already high-ranking SaaS?

Despite ranking in the top 5 for our key phrases, our CTRs are on a downward trend each month. Google's increasing focus on paid ads and its own features seem to diminish our organic results. Plus, escalating competition only adds to the dilemma.

Considering these dynamics, we're pondering a shift in our budget away from SEO and towards other potential traffic sources such as content, social media, and Google Ads. Here are the key arguments we're wrestling with:

1. Organic Space Shrinkage: Google's SERPs are increasingly dominated by paid advertisements and Google's own features, reducing the visibility and therefore the value of organic rankings.

2. High SEO Costs: SEO is becoming more complex and thus expensive. If competitors are drastically increasing their budgets, we're drawn into an escalating SEO war that might not be cost-effective.

3. Alternative Channels: We could potentially achieve a better ROI by investing in other channels such as paid advertising, email marketing, or strengthening our social media presence.

4. Instant Results: Unlike SEO, which takes time to yield results, some alternative strategies like PPC advertising offer immediate results and more control over our visibility on SERPs.

Despite these arguments, I understand the importance of SEO for long-term visibility, authority building, and keeping up with algorithm changes. However, given the points above, I'm questioning if our budget might be better spent elsewhere.

So, I'd love to hear your thoughts:

Has anyone else experienced a similar situation?
How did you respond to declining CTRs despite high rankings?
Did you continue to invest in SEO or did you divert resources to other areas?
If you chose the latter, what channels did you focus on and why?
Looking forward to hearing your insights and experiences.