That's too broad a question, and really depends on the ecosystem, but I'll narrow it down for you if you want just want one obvious use case and I can expand as I go: verifiable proof of ownership.
Something like Melvin Capital shorting 138% of GMS's stock would be impossible in a properly regulated Market, one that prohibits endless speculation and the wanton destruction of Capital for the sole purpose of making money gambling to take a business down as the outstanding shares cannot simply be willed into existence if they need to be cryptograhpically verified and exists solely on a blockchain, but most likely a sidechain/colored-coin system that still has the same properties.
Naked Short selling maybe technically illegal, but that is in name only and in continues unabated to this day, hell the SEC refused to look into this obvious collusion between various hedge funds (citadel/melvin/Steve Cohen) but speculation about trying to go after Elon for taking to Social Media and talking about Bitcoin is enough to warrant a possible investigation?
Also, deed ownership, be it land or property: government's entering hyperinflation and dissolving is a perfect time for asset forfeiture on a national level (nationalizing) by the vying faction and is responsible for so much unnecessary misery and wasted Human Capital: I wish I still had this interview that really touched me it was with Suboi, a now famous Vietnamese rapper, but relatively unknown at the time and her parent's issue with trying to convince the Vietnamese government that they owned the home before the War happened but they tried to make all kinds of excuses to repossess it as she was growing up: its the basis for her song 'Đời' talking about her father's attempted suicide and thier monetary troubles as a result of this dispute with the government.
Same thing happened in Katrina with FEMA and settlement checks as ownership of the home had been on a legacy basis that had roots from sometimes from colonial times.
Lastly, and most vivid to me is over coming censorship, but specifically financial censorship: I did it and I could write a book on the matter. But suffice it to say, I was really touched by Paxful's work recently as they just built their 4th school in Nigeria instead of 'moonboi'ing it' and buying 'lambos' with the wealth their startup created and have instead focused on help build the the Nigerian economy and it's entrepreneurs to create wealth all while their Government is actively trying to deem it as the source of all it's problems, not least of which ~12 inflation per annul that is a direct result of poor monetary policy coupled with even worse insular laws and ossified fintech solutions.
My most ambitious and craziest goal/aspiration of all is something Elon just made possible with adoptiong Bitcoin and making it clear a crypto will be used on Mars: Bitcoin serving as the medium of exchange for inter-planetary trade and commerce, and a settlements network.
Banking even in the West doesn't even work on weekends or past 5pm and people are just assuming we can keep carrying that corpse on our backs as we are slowly getting closer to becoming an multi-planteray species is beyond me and I cannot emphasize how critical that will be in just the next 2 decades.
Voting is another one that should also be clear, given Trumps fomenting of violence in the capital reminding why its best to have open and free elections that can be verified by anyone in real time. Several countries have attempted this so I'm not going to into depth as the information exists, and that's just focusing on what we've created in the last decade, I think the next 2 are going to be an even more interesting ride as I cannot even what is next and this tech moves so fast.
UBI would be another one, but to be honest Aurora failed and we didn't gain much useful info from it's failure, so this is one we have to wait for Nation states to fail (even more than the US has with unemployment apparently) at and we can quickly iterate from there as the technology is just way more robust and capable now.