You didn't read what was posted.
You responded to a reference by the OP to the guidance from the embassy on E-visas, nothing to do with extensions.
The embassy should refrain from posting the Thai requirements, every time it gets mentioned someone gets the wrong end of the stick and starts talking about extensions.
This is what the OP was asking about.
Financial evidence showing monthly income of no less than 65,000 THB (£1,500) or having the current balance of 800,000 THB (£18,000), e.g. bank statements, proof of earnings
- Applicant’s recent official UK/Ireland bank statement shows your name, address (Screenshots are not accepted). For monthly income of last 3 months no less than £1,500/ month. https://london.thaiembassy.org/en/page/retirement-visa