I attempted to do a bit of personal tweaking of the mod and failed, I didn't know math.random couldn't be used on initialization and the game errored and told me not allowed. But I'll show you what I did, and I think you'll understand exactly what I was hoping to achieve with this suggestion. I think Random would be the most fun, every time you start you'd not know how many launches you need to do before you get to that point. It could be easy, or it could be the most brutal masochistic thing ever. A 25% chance that you'll have to launch more than the hardest difficulty. However, I'm not sure where we'd have to put math.random for it to work in this setting here so, I'll leave that up to you.

if global.launchMult == nil then

    global.launchProfile = settings.startup["SpaceX-launch-profile"].value
    if global.launchProfile == "Classic" then
        global.launchMult = 1
    elseif global.launchProfile == "Moderate (x5)" then
        global.launchMult = 5
    elseif global.launchProfile == "Hard (x25)" then
        global.launchMult = 25
    elseif global.launchProfile == "Brutal (x150)" then
        global.launchMult = 150
    elseif global.launchProfile == "Masochist (x750)" then
        global.launchMult = 750
    elseif global.launchProfile == "Random (x1-x1000)" then
        global.launchMult = math.random(1,1000)
    else
        global.launchMult = 1
    end
end

{
    type = "int-setting",
    name = "SpaceX-research",
    setting_type = "startup",
    default_value = 1,
    allowed_values = {1,2,4,8,16,32,64},
    admin = true,
    description = "SpaceX-research-cost",
    order = "1",
},
{   
    type = "int-setting",
    name = "SpaceX-production",
    setting_type = "startup",
    default_value = 1,
    allowed_values = {1,2,4,8,16,32,64},
    admin = true,
    description = "SpaceX-production-cost",
    order = "2",
},
{
    type = "string-setting",
    name = "SpaceX-launch-profile",
    setting_type = "startup",
    default_value = "Classic",
    allowed_values = {"Classic","Moderate (x5)","Hard (x25)","Brutal (x100)","Masochist (x500)","Random (x1-x1000)"},
    admin = true,
    description = "SpaceX-launch-profile",
    order = "3",
},

Interesting idea. Did you try putting a requires statement to add the math library? And have you tried the mod on the existing hardest settings? Under vanilla conditions, it is a serious marathon performance - do you really want to go even further, and randomize it?

I have no idea what I tried, its been so long. xD I'm likely to be banned from factorio soon after my post on the forums about the toxic admins and moderators in discord.

I have met a few people that thought hard was easy and automated it to that extent however. So I think adding the other options I had suggested would be good. Not like adding additional options would hurt anyone since they still have the power to select the options they want.