Bitcoin market dominance is at nearly 50% now

If dominance gets higher then surely Alts will suffer and slowly die
Tell me why alts are "suffering" when they are almost all enjoying growth in price? Unless you bought alts in BTC, in which case you are trading, then yes, you may be making nett BTC losses. But convert that all back to fiat and you won't have lost as much. If that means alts are slowly dying, then it just makes a stronger case for alts: stop relying on BTC and make your own space in the crypto world.
Congratulations to alts that are not only traded in BTC.