The pack is rigged because no one needs 8 copies of Rs and Ns, they lower the odds you you getting UR and SRs you want. Sure you can get lucky but many don't.
You obviously know nothing about RNG which can not be rigged. You can't say it's rigged just because some doesn't get an UR within 20 pulls. It's all random. If this is rigged then so are ygo the cards you buy from the store.