I think that people who are defending these joy-suckers are confusing people who join in discussions on the slightly pessimistic side with those who actively seek to bring everyone down, based on no facts whatsoever.
Example: OP: Do you think my holiday abroad will go ahead in June?
Response 1: It's looking hopeful. The number of cases is just starting to come down and we have a great vaccine roll out underway. There's some evidence that the vaccine does prevent transmission and that it will be effective against the new strains. Hospital admissions and death rates will follow to come down and then we should move down the tiers. It's being reported that this could well be from the beginning of March. So hopefully by June most restrictions will be lifted. I really think that once we get the top 4 priority groups vaccinated then we will see the number of deaths much more in line with the flu, and we don't stop foreign travel for flu each year. Remember, people went on holidays abroad last summer so its highly possible that this summer will look the same.
Response 2: I'm not sure, I really hope so, but if it were me, I'd be prepared for it to be cancelled and maybe aim for a UK holiday. We are still not sure if the vaccine prevents transmission, and we won't even have all adults vaccinated until the beginning of autumn if all goes as planned with the roll-out. Most other countries are behind us in their vaccines so maybe 2022 is more realistic for holidays abroad. We may be just starting to come out of this peak, but remember that we thought the same in October and another wave came for Christmas. It is possible we come out of this lockdown too early and get another wave by June. We have no idea what other new strains may bring.
^ both valid options to me, based on some facts, and if scientists and experts can't be certain, how could we possibly know?
Response 3: I'm afraid there's no way you will be going on holiday in June. The government will open up far too early because of their own greed and we will get another wave. Sadly, the vaccine doesn't stop transmission so it will spread quickly again. The priority groups for the vaccine are ridiculous and are just leaving the virus to spread unchecked in the younger working people. If there is any air travel you will have to have a vaccine certificate to be able to fly and if you are a healthy adult under 60 then you won't be getting it for a long time. Unfortunately, even if this vaccine works, there will be a new mutations that the vaccine doesn't work for, so by the time everyone is vaccinated we'll have to start again, so what is the point? Unfortunately, I can't see holidays going ahead until at least 2025. And even then we will still be wearing masks and have social distancing, so it will hardly be an enjoyable holiday will it?
^ number 3 is who the OP means. I'm still not sure if they are mentally unwell and need support or are just very nasty people who have no reason to post responses like this other than to bring others down- maybe to how they feel, or maybe they don't even believe it themselves. There's just no need for it.