Mine altcoins and HODL in bitcoin
which ones are you thinking about?
The most profitable ones,right now DOGE/LTC ofc

At the author's price for electricity, it is profitable for him to mine any coins on any equipment

yeah he does not need the most expensive highend gear.
the l7 pulls 3.1 kwatts or 75 a day.
at a nickel that is 3.75 usd post cost.
the l7 earns 9 usd a day so a net of 5.25 a day
that is 2000 usd a day in coin net.
the L7 can be found for 2000.
so it pays off in a year which is decent.
Yes, with a budget of 3000 euros, buying 2 used ASIC L7s would be a good decision, but a beginner will need a little more money. There are still 757 days until the Litecoin halving, which is quite good for buying an ASIC.