Existence in the context that you are using it and in the source you provided are material existence.
If you require more evidence from a source that is not wikipedia to support my claim that Buddhism is not Nihilism then I refer you to verse 18 of the Pancagatidipani. It's in Pali. Verse 18 describes the burning hell that consumes a Nihilist. My translation comes from Penguin Classics: Buddhist scriptures 2004.
Verse 18 reads:
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The nihilist who asserts that the dhamma is non-dhamma [this, that the truth is untruth] and whoever torments beings is consumed by fire in Patapana.
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If you would like me to take a picture of the page let me know.
However, please do not read this reply and think that I believe that this is true. I am only sharing information and supporting my proposition that Buddhism is not Nihilism.
Well, that's pretty easy to do. Just look at the first words of
Buddha's first sermon after his awakening:
"There are these two extremes that are not to be indulged in by one who has gone forth. Which two? That which is devoted to sensual pleasure with reference to sensual objects: base, vulgar, common, ignoble, unprofitable; and that which is devoted to self-affliction: painful, ignoble, unprofitable. Avoiding both of these extremes, the middle way realized by the Tathagata — producing vision, producing knowledge — leads to calm, to direct knowledge, to self-awakening, to Unbinding.
"And what is the middle way realized by the Tathagata that — producing vision, producing knowledge — leads to calm, to direct knowledge, to self-awakening, to Unbinding? Precisely this Noble Eightfold Path: right view, right resolve, right speech, right action, right livelihood, right effort, right mindfulness, right concentration. This is the middle way realized by the Tathagata that — producing vision, producing knowledge — leads to calm, to direct knowledge, to self-awakening, to Unbinding.
So, are you producing direct knowledge and self awakening out of nothing at all?