I couldn't stress how important Wikidata (and its predecessor DBpedia) is as a public example of a huge knowledge graph (versus the ones hidden at big tech companies) but also as a Wikipedia-like collaborative project to organise all the knowledge among existing semantic web / linked data publishers, government open data, libraries, galleries, archives...

Also remember that Wikidata is open source and you can fire up your own knowledge graph as docker containers on your laptop: https://wikiba.se/

If you have been disappointed by RDF-based technologies before, I would say Wikidata/Wikibase have significantly innovated on top of them. For example, they allow each statement to have qualifiers, references, depreciation/preferredness attached to them in a user-friendly way while also keeping simple queries simple.