Only a novice trader will refer to trading as luck,
it’s definitely possible for someone newbie to start trading and then get lucky which is how they probably think that trading would be so easy and only require luck but eventually they are gonna make mistakes and they are gonna find themselves short
In addition to this, newbies most of the time are losing in trading, and who are the newbies out there who ended up winning on their first few traders? Less than 1% or 5% maybe? Nevertheless, it's a rare scenario and most of the newbies (including me) are losing money at their first try in trading.
This is also the reason why whenever I give an advice to a newbie, I always say that they must not spend too much on their first deposit because that's the time where losing is at it's peak, and they might get disappointed when they go all-in on their money and lose it all. The chances of newbies winning in trading is quite low, and isn't sustainable because at some point, they will make mistakes like you said that might cause them to get liquidated.
Overall, luck in trading is a factor, but luck alone isn't enough for a trader to make huge profits. I still believe that the 2 key factors that affects the profitability of a trader are knowledge, and experience.