Chances are that you're being sarcastic, but in the event you're not or if others want to learn...

Interesting tech. Almost zero practically useful applications.

Blockchains are effectively reproducible, verifiable ledger systems. But if the ledger grows infinitely, your storage and compute costs also grow infinitely. I've heard this has been solved, but I haven't seen an implementation yet. (If anyone knows of one, please share!)

Another issue is the proofing system. Bitcoin uses proof of work, which means you need to do more computational work to produce new blocks on the chain. If the computational work grows, that means you need more and more powerful computers. This means increased cost which means centralization as participants with less money to pay for compute get pushed out. Alternatively, there's proof of stake, where having some amount of a token or some similar value/stake allows you to write new blocks. This does reduce the computation cost but still causes those with lots of tokens/stake to get even more tokens/stake, which in turn allows them to spend more for new blocks... which creates a loop towards centralization.

So basically, the technology that preaches decentralization naturally centralizes in practical use over time.