People who only buy bitcoin for short term profit, speculating in the market and exit the market forever can not be considered as Bitcoiners but if they repeat it a long time, I think they are Bitcoiners too because they are necessary parts of Bitcoin community and market.
Yep, I was going to make the same comment, everyone who supports Bitcoin, buys it, or sells it is a Bitcoiner. We can't say to someone that they are not a Bitcoiner just because they have never run a node or mined before.
Not every Bitcoin investor can run a node, although it isn't that difficult, and it can teach someone a lot. I believe they probably have a lot of questions that can be answered if they follow a tutorial and go through the steps to run a node.
I completely agree that those who bought Bitcoin to hold it long-term are also Bitcoiners. I call myself one because I have been holding it for some time now. And yep, without their involvement, the mining ecosystem wouldn't survive in terms of profitability for miners. They all do this for a reason.