I do NOT have any siblings or cousins DNA tested
There are thousands of your cousins who have tested - that's why you have all those DNA matches.
You don't need to persuade the cousins you know to test in order to collaborate with cousins - I've never even met most of the cousins who I collaborate with on DNA. Some were found through conventional research and subsequently tested, some I only found because they were DNA matches. Thinking about it, I've never met
any of my relatives on my father's side with the exception of my grandfather, who died when I was 4 -
all of the paternal cousins I'm collaborating with were found as a result of family history.
Collaborating with close cousins helps to determine which part of your tree a match with an unknown cousin is with, but collaborating with more distant cousins is often key to knocking down 'brick walls' that are 5 or 6 generations back.
Ignore distant matches at your peril. Ancestry sort the matches according to the amount of DNA shared, but once you get beyond 2nd cousins it's a poor guide to how closely related someone is. For example, the prize-winners who attended my
DNA for Christmas presentation will know that one of my own 'distant' matches, someone who Ancestry classify as a 5th-8th cousin, is actually a 3rd cousin who I've been collaborating with him for almost 20 years, having found him through the Suffolk Surnames site. That's why it's important to follow the strategies in my
DNA Masterclass if you want to make the most of your DNA test (and why wouldn't you, having shelled out upwards of £60).
Perhaps those who don't understand DNA should either work to fill the gaps in their knowledge (the Masterclass has all they really need to know), or keep quiet on the topic? Otherwise it's rather like someone saying "I'm not going to get vaccinated because I don't understand how the vaccine works", but not trying to find the answers.