Drones can destroy tanks, but not that easily. In most cases they actually shrug off drone hits pretty well. Even old weak armoured tanks like the Leopard1 are reported to have survived over 50 drone hits. Modern systems even more. The main thing basically everybody is researching right now is a light weight anti drone gun system. This is also useful as a machine gun for a tank, which basically all tanks have anyway. If that can be added and made to work, then fewer drones would hit them, which with added armour makes the cost usefulness balance much better. Other ways of dealing with that problem are AA platforms like Gepard or the new Skyranger.

As soon as you have that, you have a platform, which can do breakthroughs on the front line and is mobile enough to exploit them. They also will work together with drones to provide indirect fire. It is much much cheaper to fire a shell on something then to use a drone. Especially for a similar sized warhead. That will be aided but larger calibers. Most modern tank designs go for 130mm or so, which gives additional range and is useful against a lot of different targets. That indirect fire role somewhat close to the front line, is how Ukraine and Russia use tanks today.