For me personally, 4G is extremely fast and cheap while being, importantly, low-latency.
Even gaming and other latency sensitive applications are possible on 4G/5G. Why not just roll out 5G networks?
Eventually, 5G will outperform fibre on a cost and speed basis (for a long time my FTTH home internet was slower than my 4G connection by a large margin). Of course, I mean practical terms rather than theoretical. Practically, fibre speeds are usually limited by 1Gbps-maximum middleboxes in community fibre cabinets that are not cheap to upgrade.