Yes it’s easy to forget the second-hand market sometimes and assume we have to buy new.
Vice-versa, in clearing out my photography “stuff” in readiness for my retirement and move to Cornwall, I’ve been amazed by how much money I have been able to raise by selling kit on eBay. And the process of doing so has been much easier than I imagined previously.
All my grandkids love Lego, the older ones started out with just basic bricks and moved onto sets, they make up and keep. The youngest one has inherited several large boxes of random bricks, ( much to his mother’s dismay). He has kits, he’s enjoyed learning to make up but spends huge amounts of time sat with his boxes, using his imagination to make weird and wonderful things. I bought a large bag of random bricks, that we keep here it gets played with by them all.
As well as eBay UK, and LBC I also use Emmaus in France.
I am happy to buy some stuff second-hand, recently some garden furniture, and to give away what I no longer need.
I still feel the pain of standing on some bricks with bare feet 
I search the room carefully, very carefully after they’ve left, this now includes checking down the back and sides of the sofa’s. It’s amazing where little bits can go.
More of a Meccano boy myself, although it should be discouraged in your children less they become poorly paid engineers and not wealthy bankers and accountants
I know what you mean and the W&G model looks like it relies on quite a few - but you can still get sets of bricks just the same as you could in the past.
I’ve bought the W&G model (well, it’s on backorder) for Mrs Butcher - she’s not especially into LEGO, but she does love W&G so it’s perfect.
