Why are people trying to downplay how awful this is?

I'm so sorry about your DH, that must have been scary & devastating.

Some people are so incredibly self centered. I'm sorry you had to endure her!

OP, just stop with your hierarchy of pain & suffering. It’s not for you to tell others how they should feel or that their suffering wasn’t as bad, according to your internal, un interrogated rules system.

HRTFT but DF died when i was in my early twenties and DM when I was in my forties, both to cancer. The loss of DM felt far harder. You don't get to tell people how the feel or make generalisations when it comes to grieving.
Nothing in my life has ever come close to the loss of DB suddenly aged nineteen. I'd spoken to him an hour before. I went to a dark place for a long time. I don't think a 'quick' death makes it easier than a long drawn out one. We never got to say goodbye or give him anything he wanted before his death. It was horrific.

Policing grief is disrespectful and doesn’t help anyone. Neither does co-opting someone else’s tragic situation as a subject of general conversation. This sounds as though it’s verging on gossip in the workplace, and fairly distasteful. Your colleague whose wife is sick might well be glad of the normality work offers, so rather than make this a competition about who can empathise the most, you could all maintain as normal and familiar an attitude as possible - that would be a less performative way to help.

When my son had cancer, I had a family member tell me they knew how I felt because their dog had cancer.

At least they hopefully won't say anything to your colleague.

Expressing shock and horror is completely normal.

You sitting there trying to engage others in conversation, waiting for them to say something you dislike, and then berating them for it in order to be the most empathetic person, is absolutely gossiping, and nasty.

I don't think it's strange at all.

I think people are more heartbroken when they hear a child has lost a parent, or when a parent loses a child.
People tend to be more accepting and understanding when an elderly person dies after a long and good life.

Of course every death is different and relationships are complex but in my experience, people are generally more able to cope with a death if it has happened at the 'normal' time.

I lost my Dad when I was 23, but that is a coarse barometer of whether 'it's terrible' or not.
My relationship with my Dad was great, so I had 23 years amazing years of love, care, and quality. I'm in my mid 50s now and some people I know are a similar age, but couldn't say they'd had anywhere near that long in a good relationship with their parents.

Which is worse? A good relationship for a shorter time or a poor relationship for longer? Some people will never experienced a relationship like I had with my Dad - that makes me lucky for having what I had.

Attention seeking from whom? Why would they need to seek attention from you about this?

Why are you even worrying about this ? It’s a very minor issue

I lost mine at 8, I think that makes me the winner.

What a repulsive thread.

"The colleague I was speaking to agreed it was awful and said she knew how they felt because she’d lost her father in her 40s. I lost my mother in my 30s and I said it wasn’t the same as being 23"

This is exactly what you're saying here: your colleague doesn't understand because her situation wasn't as bad

I can read you deciding a hierarchy

I agree. I lost my dad at 17, doesn’t give me the right to pronounce that my loss was worse than anyone losing their father at any age.

What do you want people to say if you're not going to stop gossiping about another family's situation?

You seem to have appointed yourself as some kind of gatekeeper of what people are allowed to say, so why not just dish out a script of what you find acceptable rather than making other people feel like shit for not empathising in a way you deem appropriate.

Losing parents suddenly at whatever age is equally horrific but in a different way. No time to prepare, get your head around things, say goodbye. It's bloody traumatic.

I think they are trying to display some kind of empathy for the situation.
sadly I had more than a few school friends who lost parents in early/mid teen kind of age.

I don’t think it matters what age you lose a parent or close family member, you aren’t equipped to deal with it till it happens

I find it strange that you seem to think certain deaths are "easier" than others. I think it's very individual - for example my mum was way closer to her gran than either of her parents, and was more upset when her gran died than when her parents did.

I'm also not an animal person but some people genuinely grief a dog dying - personally I think that's ridiculous, but everyone experiences grief differently and I think it's a bit strange when others chime in with their own experiences of grief to say "no you don't understand because your grief wasn't as bad". There isn't a ranking system for grief