As John correctly stated the main applicant needs 2 years of passive income of $80k to qualify for the LTR-P visa, if you are applying as a dependent and not for your own LTR-P visa you can apply based on the main applicants visa.
Just to clarify the LTR-P financial requirements, you each need to demonstrate $80,000 USD passive income for the last two years before applying for the visa.
“Applicant must have a bank deposit of not less than 3 million Baht in Thailand or a bank deposit of not less than 1.8 million Baht and an annual income of not less than 1.2 million Baht per year. Such amount must be maintained in bank deposit in full for at least one year and kept at not less than 1.5 million Baht thereafter.”
US Thai Embassy
I guess it depends on which embassy website you read the requirements.
Get the 90 day Non O based on retirement from your home country embassy instead of the 60 day tourist visa. Then, once in country, you only have to worry about applying for the 12 month extension of stay.