Why is Ulysses foolish for setting out on a journey he knows he cannot complete in the poem by Lord Tennyson?

Greek hero Ulysses and his band of soldiers had spent ten years in the Trojan War. Returning home they were lost in the sea and had to spend a few more years in roaming the sea. At last they sighted land. It was the land of Lotos Eaters. From the height of their anchored ship they could see far into the interior of the island. It was an island of mountains, rivers, valleys, wind and waves. Streams and falls were everywhere. Green woods and meadows ornamented plains and hills. It was a land where all things always seemed the same. No signs of cultivation or other human activities were to be seen anywhere there.

Those famous soldiers who fought bravely beside Ulysses in the fierce Trojan War now no more wish to bear the burden of sailing their ship through turbulent seas. Mariners declining to resume travel is the dread of all sea-going captains. Why return after years like apparitions to their native island of chaos? But Ulysses is a very persuasive person. He used every trick and argument in his quiver to tempt his mariners to return to Ithaca. But they warn their captain that it would not be wise for them to return to their island home of Ithaca. Everything might have changed there. Their sons would have inherited them after all these years. The returning ancestors would only be viewed as ghosts and apparitions come to trouble their joy. Or else the over-bold island princes of Ithaca, fearing no return of the heroes might have married their wives and spent their fortunes. Their great deeds in wars would have been half-forgotten, sung only in songs. Even if they are lucky and oriented enough to return to their land, it would be harder still to please their gods after all these years and settle order once again in their island. So why not spend the rest of their lives in this quiet island of Lotos and enjoy sleep and laziness to their fill? From history we know that Ulysses and his sailors did return to Ithaca, but only after so many years. So naturally the question comes to whether he was foolish in either sailing from Ithaca for the war years back or in persuading his soldiers to leave the quiet and peaceful island and return to native Ithaca years after.